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Discussion Starter · #1 ·
Hi there, been reading these forums for a long time and decided to finally post, I have a 2008 700xx which I got about a year ago and at the time I knew nothing about xx's, the guy said It needed a new power commander and battery so I brung it home and had a better look at it. The wiring was a MESS at the front end as quad was raced specd with also no headlight to protect it all from the elements but we got around to getting it running by taking the faulty pc3 off of the quad and unfortunately at this point I have no idea how important a power commander was seeing as it has a full fmf system on it but I proceeded to use it for probably about 5-6 hours (not at once lol) untill I started experiencing problems with it spluttering at high end which proceeded to get worse untill it stopped running so me and friends spend ages looking for the problem at which point I also found the forum and proceded to order a pc3 thank god lol but yeah I tested things like the fuel system and electrical system figured it must be the ecu which is playing up so ordered a new one for 拢100+ + 拢60+ for shipping to the UK then as I went to install it my friend cut the loom to the ecu open about 5 inches up at which point we noticed 1 rusty wire so soldered it and boom it runs fine on the old ecu so set up the pc3 and finally got to ride it again but it was getting pretty hot still and wasn't running all too great and was killing batterys so I have tried changing my fuel map, adjusting valve clearance, oil and filter change then unscrew the oil level check bolt, cleaned fuel pump, checked voltage at battery and stator plug (I believe it was not to specification at stator which could help explain killing batteries) but none of this has really helped and recently I added a quite core to my fmf and not long after it has started spluttering in gear anywhere over like 2.5k like a limp mode. I have a new waiting harness and lights waiting to go on but instead I think I will finally open up the motor and see how bad it is 馃槵 but Any help or experience would be GREATLY appreciated as I would love to experience it running perfectly one day

Also I don't suppose anyone has a drop link for a sway bar for sale or else it'll end up costing me nearer to 拢100 with postage

Many thanks, Tom
 

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Can you post some more pictures of that rear crash bar?

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I'd test the compression before doing anything else. If you could more clearly describe exactly when it does what it would help as well. Background helps for avoiding troubleshooting the wrong thing, but really focusing on what it does when and what changed exactly after anything was done to alleviate it would help.
 

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Discussion Starter · #5 ·
M-quick I'll take some better pictures of it later on.
Deephaven the pressing issue is that it will run and ride just fine for about 10 minutes /until it is hot then suddenly it'll splutter so I'll come to a stop then whenever you try to ride off it'll start bogging/spluttering over 2k rpm and will often just backfire and die but if you put it into neutral it will rev up seemingly fine which is why I think it could be a failsafe and it started happening probably 1 hour of use after installing a exhaust baffle and also I tried making minor adjustments to the fuel map to compensate for the restricted flow and it seemed to run better for the first 10mins but then went straight back to spluttering, I have been meaning to take it for a dyno session but that's easier said than done in the UK
 

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When's the last time you put a fresh plug in it?

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Is it completely fine cold? I'd still test compression before doing anything else other than changing the plug. Other tests, check for voltage at rpm. A weak alternator can cause issues and regular will show up when hot. I'd also ask if the fuel lines are stock. If they are someplace where the fuel can boil (I have no idea how they are routed on the machine) the same issue can surface.
 

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Discussion Starter · #8 ·
I have never put a fresh plug in actually only cleaned the current one as it has some fancy 4 point high proformance plug lol but I'll try putting a different one in later and yeah it has stock fuel lines but with a extra filter between tank and pump I'll take a picture of that too later and I'll also test the voltage at different rpms and when it is warm and I'll let you know the results
 

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Discussion Starter · #9 ·
And yes seems to be fine when cold no spluttering for at least 7 mins of riding
 

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Positive that the water temp is okay as well? Not some forced limp mode?

...a quick caveat, I am a motor head but have only had a 700xx for a couple weeks and don't know what it does in which situations. Just offering troubleshooting and thoughts I have experienced on other types of machines.
 

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Discussion Starter · #11 ·
No I'm not positive I do think it could be a issue with the cooling system I'll try and test the thermostat tonight and yes I figured from one of your other posts but I still greatly appreciate the assistance lol
 

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Discussion Starter · #12 ·
Well I did a fair bit to it tonight I tested the voltage when cold and hot and revving and it strayed around 15v so that's all good, I adjusted my valve clearences and that seemed a bit certianly made it easier to start so they must have been out. Flushed the coolant system and tested the thermostat in the kettle and it opened but I didn't have access to a thermometer so I suppose I'll have to test it again sometime, and did a compression test and got 90psi dry and 95psi with oil in the cylinder I have no idea what good compression is in a xx tho. Haven't had a chance to test it properly yet to see if it splutters as it's all in bits still but I'll test it tomorrow and let you know
 

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I would slap that compression gauge on something else and check it. About 30-40lbs low...buy with only one cylinder it may be the gauge. My buddies is about 20psi low on his gauge. With a 2 cyl you can at least make sure it is balanced. That low though it is doubtful it is the gauge.
 

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That is one heck of a custom race bike you have there! I think you may need an engine rebuild based on those psi values. Anything below 110 psi is usually not good.
 

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Discussion Starter · #16 ·
Thanks bud I'm glad you appreciate it ahah and yeah at least I'm certain on that now so I guess I'll just have to let it sit till I save up enough to give it a rebuild im just worried if it has modded internals too now
 

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Discussion Starter · #17 ·
Also I'm sure it's not the compression gauge that's messing up cos I was reading 100+ on a 250 farm quad lol
 

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Bummer on the motor. Did sound like that was probably the case. Conveniently it is a single cylinder and looks pretty easy to do!
 
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