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Thumper Racing 730 kit

44K views 175 replies 35 participants last post by  M_Quick 
#1 ·
So as you all know, I have the kit. Got it back this past friday and wasn't able to ride it. I was there for the final stages of putting the head on and stuff, and damn stripped the nut to the outside of the crank, so the valves are off a tad until I can get a new cover bolt (already ordered).

I will just say what I needed done to prevent creating another thread. I blew the oil ring of the old piston plus a knick in one of the compression rings. Don't really know how, but it happened. Also, the crank where the wrist pin goes in was scratched up a bit, so I got a new crank.

So here it is. I did a lot of stuff to this bike besides just the kit, which I will disclose at some other time. With the kit, I got a stage 3 cam, and the place was suppose to charge $405 for the kit and to bore out the cylinder, plus $185 for the cam (which is a hot cam). Anyway, they called me up and said I owed $490, which was awesome, it was 100 less than I though. Turns out they didn't charge me for the boring, the kit itself was $285 with out them boring it out. I also talked to the guy there quite a bit, and he is very nice and informative.

So with everything installed, I finally got to ride it. It is a lot harder to start. I dont know if it is b/c the starter is having more of a problem due to a higher compression, or if the starter is just going. It has tons more power than it did with just the big three. I was ripping around in the yard and the rear would kick loose in 3rd and 4th a lot easier, and it was way easier for wheelies as well. Overall I am pretty impressed, with the price it was about as much as it would be for just getting the OEM piston and rings. I can't think of much more to write, so if anyone has questions, feel free.

Oh yeah, it sounds a little meaner as well.
 
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#28 ·
Thanks Bo, I have a buddy that has a flat track set up, I am going to try to use his tires.
 
#29 ·
and u lose about 3hp with knobbies on a dyno
 
#34 · (Edited)
Best of luck, might help

Hey 45, hope the 730 kit goes well as that's the kit I want to put in my rig next year. Mate you said you had starter problems, before you look at the starter have a look at what amps your battery is churning out, it could be the problem as I have found the standard battery to be weak.

I own a Aprillia RSVR and they are renound for having a weak battery that barely turns over the motor.
I changed to a High Performance battery and as an example the old Yasa was churning out something like 1200 miliamps (just an example).

I buy this new High Perfromance battery (expensive and I forget the name but can find out I know its made in the US) and it boosted straight to 2000 miliamps it now turns over my Vtwin like its a single and holds charge better. Might just help. Mate the battery was a DEKA
 
#35 ·
Sorry Gents, still no Dyno test. Maybe after Tennesse. I adjusted the exhaust valve and that let off some of the compression so it is starting much better now. I checked everything else before hand to be sure that was external, and then the decompression spring as well on the cam. I did this little trick, tried it, and she starts up like a champ now. It definately has more power and everything, so soon enough we will see. I just bought a new truck so the funds have gone into that for a down payment lol.
 
#37 ·
thumperracing.net. They are very reasonable. If you get the cam from them they will probably give you a discount like they did me.
 
#38 ·
Have u ridden much since the kit? Has it been running hotter? Does it seem as reliable? Why did you choose the stage 3 cam compared to the stage 2? I am looking at ordering my kit next week so I was just trying to get an idea of everything. Is there a huge difference in power compared to stock? I have the programmer and lid already. I am going to get the full barkers and the thumper. I was trying to decide to just go hi compression or to do big bore. The more info you can give me the better. I appreciate it
 
#45 ·
I have about 15 hours on it since the rebuild. Now the main reason I even did the kit VS. say just piston and cam, is that it was pretty cheap, pretty close to the same price, and I don't mind being a guinnea pig. Now I went w/ both stage 2 and stage 3 cams, trying the difference between the two. It seems pretty reliable. I had a problem with it starting at first, but get it tore apart and found out the exhaust wasn't in the tolerance it should have been. It doesn't seem to be running hotter. I am definately switching back to the 14t, and it does have more power. I was riding some back roads the other day in 5th, cruising around w/ some buddies and nailed the gas and I could feel her spin a tad b4 the tires regripped. I then tried some wheelies w/ it down the road in 4th and 5th and it didn't really have a problem coming up. If you can wait till a week from this sunday, I will be running it everyday down on the Tennesse trip, and can give you a better report on it. If you do just better compression and cam, that is pretty much what other poeple do, such as boost, and that is tried and proven. I can't give you HP gains or anything as I haven't had it to a DYNO yet.
 
#44 · (Edited)
I followed what Wayne M. had sucess with. It's been race proven and just works. Most of the power is in the head work and cam.
Now these # are with a p&p head with +1mm intake valves,springs and 11:1 cp piston (tb will get you 1/2 hp@ most)
Webb stage 2 cam=54-56rwhp Over all rpm gains
Webb stage 3 cam=57-59rwhp mid-upper gains
Webb stage 3+ cam=60-61rwhp 8-10 hp increase over stage 2 cam after 5000-6000rpm:hey:
 
#46 ·
I just ordered different valves from Honda, and got both cams right from Thumperracing.
 
#49 ·
My explanation of compression.

Compression is simple really. Take your hand and put it over your mouth. With all of the air out of your mouth, use your tongue like a piston and try to draw air in. You will notice a vacuum will build instantly trying to get air through your mouth which is against your hand.
Now with your hand still over your mouth try this. With your mouth being half full of air do the same thing with your tongue. You will notice more delay of vacuum building in your mouth- the more air currently in there, moreso on the delay.
This is compression working on the intake stroke. The more compression you run in an engine the less "air" will be left in the chamber/cylinder after the previous exhaust stroke. With this then the higher the compression the faster the chamber/cylinder will pull vacuum and bring fresh air/fuel in. In return on this the fact the fresh air/fuel will be less contaminated by residual gas left over from the previous exhaust stroke the higher compression you run. The exhaust works better by removing more burned gases from the chamber/cylinder with higher compression and the intake has a faster recovery time on vacuum with less area in the chamber/cylinder to be filled at TDC.
Another thing about compression is also trying to be as effecient as possible at attaining it. Say you have an engine thats got a .040" thick head gasket, 60cc chamber volume, and the piston being .040" from the top of the cylinder at TDC and you have another engine with a .040" thick head gasket, 60cc chamber volume, and a piston being dead on .000" at the top at TDC. Both engines having the same static compression ratio which will make more power? The second engine because mainly the flame travel involved and the quench the second engine has by removing air/fuel as much as possible between the cylinder head deck and the top of the piston to get it into the chamber were it can be as close as possible to the spark plug. There will also be an advantage of having a smaller dome on the piston for flame travel and airflow across the piston.
Now that you see the advantages that more compression plays in the exhaust and intake cycles of the engine now lets look at this. Say you have an engine thats perfectly matched in cam profile, rpm use, compression, porting, intake assembly and exhaust assembly. Take that same engine and increase the compression and you can reduce the overlap of the camshaft, make more power everywere and have better driveabilty all at the same time.....wtf you say? Heres why, remember I said that the more compression you run the less residual burned gases are left behind after the exhaust valve has closed. In return you have less deluting of the fresh intake charge thats coming in. Overlap is just that, its taking up the slack of this residual gases being in the way and also getting a head start on the intake port/valve delivering the fresh air/fuel.....all while the piston hasnt really done anything but sit at TDC while both the exhaust and intake valves are open(did you know that happens?). Yes, its cheating mother nature by creating a siphoning effect of the exhaust valve being open all this time and the burned gases rushing out in that direction. The intake valve cracks open just before the exhaust valve closes and with all of this motion toward the exhaust going on in the chamber it siphons(sucks) some fresh air/fuel in by the intake valve and by the time the fresh air/fuel reaches the exhaust valve its closed and the piston starts its way down the cylinder creating a low pressure point(vacuum) in the chamber and the intake valve continues to open and delivering the fresh charge into the chamber/cylinder. The problem with this is designing the right amount of overlap in the cam profile to get the right amount of timing events to make that happen without fresh air/fuel going straight out the exhaust before the exhaust valve closes or not getting enough overlap to get as much as possible of the residual gases pushed out the exhaust valve before it closes.
What you have to understand is it takes time to get air and fuel to move, the faster the engine revs the less time it has for all of this to take place. The faster the engine is spinning(rpm) the more amount of overlap thats needed to effeciently do this....to a point. The more compression you have, the less residual burned gases are left over to be moved out of the way so in return there is less need of overlap.
The compression of an engine is were it gets the power to move the piston down the cylinder on the power stroke. The more cylinder pressure you can create the more force there is against the piston to move it down and in return turn the crank(torque). Horsepower is something that cannot be measured, it has to be calculated off of torque remember. Compression sounds like one of things you cannot have too much of but its not. Remember, diesel engines have roughly 20:1 compression and they dont have spark plugs for a reason- the cylinder pressure along with adding the fuel at just the right time basicly is all it uses.
Preignition will kill an engine.
Even with top of the line parts all your doing is delaying the kill. Spark knock is were theres either too much compression, too much ignition timing, too much load against the engine or too lean of a air/fuel mix or a mixture of all. What happens is there is so much cylinder pressure building up in the chamber/cylinder that the air/fuel ignites itself usually in the far edges of the piston and chamber and the flame travel starts heading toward the spark plug. By this time the plug has fired and ignited the mixture around itself and the flame runs into the flame coming from the other direction and bang, its lit too soon and tries to push the piston down before it reaches TDC and thats bad...and noisy.
On the other hand the more compression you have the strong and more violent the burn is to create energy to move the piston down the cylinder to create torque, thats right, torque through the crank. If its too violent then you know what happens.
The catch in all of this is there are two types of compression in all types of internal combustion engines:
Static and dynamic
Static compression is what most of you are used to dealing with. The actual measured amount of displacement of the cylinder and chamber. How much amount is in the cylinder and chamber at BDC divided by the amount thats in the cylinder and chamber at TDC.
Dynamic compression is static compression with the amount of cylinder pressure thats bled off by the cams overlap and duration of the lobe profiles. Yes, its a little more involved but its a more precise way of showing how much compression an engine really has.
Remember, power is generated by cylinder pressure in its simplest terms. The larger the camshaft profiles are the longer the valves are open and in return of all that good stuff is you also have more and more pressure bleed off. How did all of those '60s muclecars run around on the street from the factory on pump gas and 11:1 or more compression along with iron heads? The cam was bleeding off cylinder pressure and the use of leaded gas. How does all of these crotch rockets and450s run around doing the samething today? Camshaft profiling and technology in FI and combustion chambert shapes.
 
#51 ·
My explanation of compression.

Compression is simple really. Take your hand and put it over your mouth. With all of the air out of your mouth, use your tongue like a piston and try to draw air in. You will notice a vacuum will build instantly trying to get air through your mouth which is against your hand.
Now with your hand still over your mouth try this. With your mouth being half full of air do the same thing with your tongue. You will notice more delay of vacuum building in your mouth- the more air currently in there, moreso on the delay.
This is compression working on the intake stroke. The more compression you run in an engine the less "air" will be left in the chamber/cylinder after the previous exhaust stroke. With this then the higher the compression the faster the chamber/cylinder will pull vacuum and bring fresh air/fuel in. In return on this the fact the fresh air/fuel will be less contaminated by residual gas left over from the previous exhaust stroke the higher compression you run. The exhaust works better by removing more burned gases from the chamber/cylinder with higher compression and the intake has a faster recovery time on vacuum with less area in the chamber/cylinder to be filled at TDC.
Another thing about compression is also trying to be as effecient as possible at attaining it. Say you have an engine thats got a .040" thick head gasket, 60cc chamber volume, and the piston being .040" from the top of the cylinder at TDC and you have another engine with a .040" thick head gasket, 60cc chamber volume, and a piston being dead on .000" at the top at TDC. Both engines having the same static compression ratio which will make more power? The second engine because mainly the flame travel involved and the quench the second engine has by removing air/fuel as much as possible between the cylinder head deck and the top of the piston to get it into the chamber were it can be as close as possible to the spark plug. There will also be an advantage of having a smaller dome on the piston for flame travel and airflow across the piston.
Now that you see the advantages that more compression plays in the exhaust and intake cycles of the engine now lets look at this. Say you have an engine thats perfectly matched in cam profile, rpm use, compression, porting, intake assembly and exhaust assembly. Take that same engine and increase the compression and you can reduce the overlap of the camshaft, make more power everywere and have better driveabilty all at the same time.....wtf you say? Heres why, remember I said that the more compression you run the less residual burned gases are left behind after the exhaust valve has closed. In return you have less deluting of the fresh intake charge thats coming in. Overlap is just that, its taking up the slack of this residual gases being in the way and also getting a head start on the intake port/valve delivering the fresh air/fuel.....all while the piston hasnt really done anything but sit at TDC while both the exhaust and intake valves are open(did you know that happens?). Yes, its cheating mother nature by creating a siphoning effect of the exhaust valve being open all this time and the burned gases rushing out in that direction. The intake valve cracks open just before the exhaust valve closes and with all of this motion toward the exhaust going on in the chamber it siphons(sucks) some fresh air/fuel in by the intake valve and by the time the fresh air/fuel reaches the exhaust valve its closed and the piston starts its way down the cylinder creating a low pressure point(vacuum) in the chamber and the intake valve continues to open and delivering the fresh charge into the chamber/cylinder. The problem with this is designing the right amount of overlap in the cam profile to get the right amount of timing events to make that happen without fresh air/fuel going straight out the exhaust before the exhaust valve closes or not getting enough overlap to get as much as possible of the residual gases pushed out the exhaust valve before it closes.
What you have to understand is it takes time to get air and fuel to move, the faster the engine revs the less time it has for all of this to take place. The faster the engine is spinning(rpm) the more amount of overlap thats needed to effeciently do this....to a point. The more compression you have, the less residual burned gases are left over to be moved out of the way so in return there is less need of overlap.
The compression of an engine is were it gets the power to move the piston down the cylinder on the power stroke. The more cylinder pressure you can create the more force there is against the piston to move it down and in return turn the crank(torque). Horsepower is something that cannot be measured, it has to be calculated off of torque remember. Compression sounds like one of things you cannot have too much of but its not. Remember, diesel engines have roughly 20:1 compression and they dont have spark plugs for a reason- the cylinder pressure along with adding the fuel at just the right time basicly is all it uses.
Preignition will kill an engine.
Even with top of the line parts all your doing is delaying the kill. Spark knock is were theres either too much compression, too much ignition timing, too much load against the engine or too lean of a air/fuel mix or a mixture of all. What happens is there is so much cylinder pressure building up in the chamber/cylinder that the air/fuel ignites itself usually in the far edges of the piston and chamber and the flame travel starts heading toward the spark plug. By this time the plug has fired and ignited the mixture around itself and the flame runs into the flame coming from the other direction and bang, its lit too soon and tries to push the piston down before it reaches TDC and thats bad...and noisy.
On the other hand the more compression you have the strong and more violent the burn is to create energy to move the piston down the cylinder to create torque, thats right, torque through the crank. If its too violent then you know what happens.
The catch in all of this is there are two types of compression in all types of internal combustion engines:
Static and dynamic
Static compression is what most of you are used to dealing with. The actual measured amount of displacement of the cylinder and chamber. How much amount is in the cylinder and chamber at BDC divided by the amount thats in the cylinder and chamber at TDC.
Dynamic compression is static compression with the amount of cylinder pressure thats bled off by the cams overlap and duration of the lobe profiles. Yes, its a little more involved but its a more precise way of showing how much compression an engine really has.
Remember, power is generated by cylinder pressure in its simplest terms. The larger the camshaft profiles are the longer the valves are open and in return of all that good stuff is you also have more and more pressure bleed off. How did all of those '60s muclecars run around on the street from the factory on pump gas and 11:1 or more compression along with iron heads? The cam was bleeding off cylinder pressure and the use of leaded gas. How does all of these crotch rockets and450s run around doing the samething today? Camshaft profiling and technology in FI and combustion chambert shapes.
Alba racing told me that Wayne's Trx700 with 12:1 blew up a couple times.
I know how compression works, i was just letting the trx 700 crowd know to go above 11:1 on the compression. I run 9:1 compression in my Cobra, but with 18lbs of boost:hey:
 
#50 ·
wow.... small post
 
#66 ·
Theres a reason why 12:1 didnt last, weither it was a clearance issue, assembly issue or a parts issue.
Building a bike that last for 4 seconds in a race is alot different than builing one that will last for 1000 mile race;)
It still comes down to my statement no matter the use of the engine. Like any NASCAR engine builder will tell ya they can come close to 1000hp with the same parts but it wont last 500 miles.
 
#60 ·
Building a bike that last for 4 seconds in a race is alot different than builing one that will last for 1000 mile race;)
even in only 4 sec them bikes still blow up
 
#61 ·
I would buy parts from Alba anytime good prices and service but one thing I did'nt like was everytime you talked to a different person you got a different story. Its hard to know what to believe when it comes to engine building when you get three different stories. Also has anyone ever posted dynosheets on the forum of a 60+ hp 700xx. I hear of so many but can't find any dynosheets. Please post a link if you find one.
 
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