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Discussion Starter · #1 ·
First like to say hi.. just bought my first raptor and im new to the forums.
I did alot of research and still am dumb founded by this.
The starter turns over slow as if there is too much compression to start. Also the battery cable would get real hot. I did get it to jump start off my truck after idleing for a min or two it died tried to jump start again and it went back to the slow cranking .
I have just replaced the battery cable to the relay with a more heavy duty one as well as bought a brand new grizzly 660 300cca battery. I put it in it fired right up. Ten one min of idle it died again. Trued to restart and it was slow cranking like there is too much compression.. please help
2002 raptor 660 with 686 kit.
I was told that the starter itself may just be too weak. But don't know what else to check.. also when it does fire up if I hit the gas it will pop and backfire slightly ... but also not warmed up obviously
 

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First like to say hi.. just bought my first raptor and im new to the forums.
I did alot of research and still am dumb founded by this.
The starter turns over slow as if there is too much compression to start. Also the battery cable would get real hot. I did get it to jump start off my truck after idleing for a min or two it died tried to jump start again and it went back to the slow cranking .
I have just replaced the battery cable to the relay with a more heavy duty one as well as bought a brand new grizzly 660 300cca battery. I put it in it fired right up. Ten one min of idle it died again. Trued to restart and it was slow cranking like there is too much compression.. please help
2002 raptor 660 with 686 kit.
I was told that the starter itself may just be too weak. But don't know what else to check.. also when it does fire up if I hit the gas it will pop and backfire slightly ... but also not warmed up obviously
I suggest you take the carbs off and clean them properly first, dismantle and clean all jets, passages, remove the fuel screws and clean them also, clean the pilots jets ,these control the idle fuel delivery, change teh engien oil and filter and pay attention to what comes out with the oil, see if there is any crap like shavings...................
 

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Master of the Electron
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Pull the spark plug and see if the engine now cranks over nice and fast... this will give you a clue as to whether the problem is compression related or somewhere else.

BTW, make sure that spark has a path to ground when you do this (example: put plug with boot attached on the head so the spark can get to ground from the plug... or put a screwdriver in the boot leaving part of the driver touching the engine). The spark's extremely high voltage, with no place to go, has been known to feed back into the CDI, damaging its delicate electronics.

Another option, when testing with the spark plug out, is to simply unplug the orange wire from the coil, so spark is never generated... just remember to plug it back in when you're done, or you'll be kicking yourself after hours of 'why doesn't it run' troubleshooting.
 

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Discussion Starter · #5 ·
I pulled the spark plug real quick just to see what that would do. It cranks over no problem with the spark plug out. I thought it had a slightly weak looking spark when I was cranking it but really not certain I put a new plug just cuz I had one laying around. Put the new plug in and wouldn't even crank over once. As if there's just too much compression... ????? Help
 

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Master of the Electron
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Check your valve clearance. If it is at spec, then I suggest your decomp pin (or mating rocker arm) is worn or just too short (or decomp is removed or somehow not working properly).

You can tighten up the exhaust valve clearance some (especially the left one, the one closest to the sprocket - it's the one driven by decomp) and, if the decomp is working, you will get more decomp... perhaps that would be enough to allow it to start?

When cold, you can take the exhaust clearance down very close to zero, because the clearance opens up when the engine warms up (and as the ehaust valve wears). Since you say it cranks well when cold, but the moment it warms up it won't crank, this may well be the issue - decomp reducing when warm... reducing the exhaust clearance will increase the amount of decomp.

The proper repair may be to replace the decomp pin with new and/or longer, but reducing the left exhaust valve clearance is, at the least, a temporary test that may tell you what's going on. Leaving it this way is up to you (if it works) and won't likely cause any issues.

Also, increasing intake valve clearance can reduce compression, albeit slightly, but it would only work for your situation if clearance is opened far enough to get the intake valves to close fully before BDC is reached; and I assume with the overlap this may require a lot of clearance... for this reason, I wouldn't suggest it except as a last ditch effort. AND you don't want to go too far or it will get noisy and you risk peening the valve stems.
 

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Master of the Electron
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Tighten up the clearance on left exhaust valve - if all starts working better, decomp pin is probably too short.

It is in the cam - remove valve cover and cam, measure and replace pin if necessary.
 

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Discussion Starter · #9 ·
Im goin to check my valve clearance today. What do you suggest I set it at? Also how hard is it to locate the decompressor pin? Can I change it while im in there?
 

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Discussion Starter · #10 ·
ok well i checked all the clearances and tightened up the left exhaust some.. still nothing. i did pull it around with my other 4 wheeler and jump started it would fire up but never got it to actually ride it would die as soon as put load on it trying to go when in gear... i could rev it up while sitting still with clutch in and it would rev up fine but sounds like there is alot of popping.. im not sure if its supose to sound this way because this 4 wheeler is new to me.
 

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Master of the Electron
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No, it doesn't normally pop a lot. Did it actually rev up to high RPM or did it start sputtering/popping and never get very far in RPM above idle? This could be one of the RPM limiters due to a loose wire or faulty switch.

It sounds as if you have multiple issues. Has this bike ever started properly or run well for you since you bought it?

Willy is most likely correct regarding the need to thoroughly clean the carbs - without this, other problems will be masked and hard to deal with. By thorough, we mean COMPLETELY - disassemble everyhing, but leave the pair of carbs together. Remove all jets, slides, valves, etc. and clean everything till they shine - pay special attention the to jet (esp pilot jets) as their tiny passages may need to be rodded out with copper strands (like from speaker wire). You can't clean these enough.
 

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Discussion Starter · #12 ·
I have no clue what's going on wit this 4 wheeler cuz I bought it this way.. I cleaned garbs did a valve job new bigger battery checked connections etc... how can I tell if the timing is right or if its slightly off?
 

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Master of the Electron
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I have no clue what's going on wit this 4 wheeler cuz I bought it this way.. I cleaned garbs did a valve job new bigger battery checked connections etc... how can I tell if the timing is right or if its slightly off?
How exactly did you 'clean the carbs'?

What do you mean by 'did a valve job'?

Check cam timing with screwdriver in plug bore, on piston. Turn crankshaft by hand CCW and watch for I in window to hit the same time screwdriver reaches maximum lift.
 

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The only thing that can change the timing is for the woodruffe key to be sheared, the timing itself can not be varied unless you change it using a programable CDI......
 

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Discussion Starter · #15 ·
I checked all the valve clearances and tightened the exhaust slightly. Pulled the carbs apart and cleaned them thoroughly with brake cleaner etc. I think the guy I got it from bs'ed me about it previously running good on the fresh rebuild. Most I have gotten it to run was maybe 2 minutes. And certainly did not sound/ act properly
 

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Did you remove and clean (inside and out) each jet (pilots especially) until you could see light through the tiny passages?
 

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I pulled the spark plug real quick just to see what that would do. It cranks over no problem with the spark plug out. I thought it had a slightly weak looking spark when I was cranking it but really not certain I put a new plug just cuz I had one laying around. Put the new plug in and wouldn't even crank over once. As if there's just too much compression... ????? Help
Honestly I would check valve lash, I beleive on the 686 the exhaust should be 18mm and intake should be 10mm.
 

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Master of the Electron
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18mm is 3/4", Christian... um NO! Here's the specs according to the manual:

140958


Oh, BTW, this thread is TEN years old...Runnin13 (the original poster) hasn't been back since then.
 
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