[Rotax Raptor]

A friend bought a motor that was built with a 14 to 1 piston, 4 mm crank, stock bore, stage 3 intake and stock exhaust cam and the motor will not crank over as is should. He bought a new starter, highier cranking amp battery and still the same problem. It sounds like the compresion is high and the starter cant crank the motor. Any thoughts?

[dylan]

Check the valve clearances, decompression pin adjustments, or timing.

[Rotax Raptor]

Thanks. I'll pass that along.

[cockeyed racing]

dylan, on 04 March 2010 - 08:52 AM, said:

Check the valve clearances, decompression pin adjustments, or timing.

I am the lucky one with the starter not cranking fast. Checked valve clearences intake=.0055 exhaust=.0095. Timing set correctly. Decompression pin seams to function properly,opens valve .016. Had someone suggest a kick starter,is this what I need? Any suggestion?Leaving in a week for week long trip.

[dylan]

i just fought the same problem with my bike. u can try tightening that one exhaust valve a little. mine would start with the kicker but i didnt have enough azz to kick it when the bike was cold. once it warmed up it was easier. i tightened that valve a little and problem solved, now it turns over and starts soon as the button is pressed. Are u running a long rod crank? check timing, may need to degree the cams.

[cockeyed racing]

dylan, on 04 March 2010 - 07:47 PM, said:

i just fought the same problem with my bike. u can try tightening that one exhaust valve a little. mine would start with the kicker but i didnt have enough azz to kick it when the bike was cold. once it warmed up it was easier. i tightened that valve a little and problem solved, now it turns over and starts soon as the button is pressed. Are u running a long rod crank? check timing, may need to degree the cams.

Are you saying to thighten the valve on the decompresion side? Timing seems to be perfect. I am also running a 45mm packard lectron ,fci intake,dynatek programable cdi,resitor kit,jsr pipe big can and have a inmotion drag pipe to play with. Bike will start if battery charger is on for atleast 30mins and run great. nice puff of black smoke when you wick the throttle. seems to wander alittle when returning to idle. maybe to lean on the bottom? as far as the crank all i was told is that it had a 4 mill hotrods crank will try and find out. also keep in mind have 200 cca battery. stock is only 85 cca. Thanks!

[cockeyed racing]

just got done puttin it thru a heat cycle. started perfect ran great still wanders alittle after wick of the throttle down to a idle. it was able to start 2 times without charger. if it was to lean on the bottom could that cause it to turn over hard?

[Radar]

It won't make it turn over hard but lean on the bottom will make it very hard to start.especially when cold.

[dylan]

smcla1977, on 04 March 2010 - 08:36 PM, said:

Are you saying to thighten the valve on the decompresion side? Timing seems to be perfect. I am also running a 45mm packard lectron ,fci intake,dynatek programable cdi,resitor kit,jsr pipe big can and have a inmotion drag pipe to play with. Bike will start if battery charger is on for atleast 30mins and run great. nice puff of black smoke when you wick the throttle. seems to wander alittle when returning to idle. maybe to lean on the bottom? as far as the crank all i was told is that it had a 4 mill hotrods crank will try and find out. also keep in mind have 200 cca battery. stock is only 85 cca. Thanks!

yeah i was saying you could tighten the valve on the decomp side a little. sounds like you got it fixed. I'm running a ltr450 battery, not sure the cca, but the starter was doing the same thing you described. only way it would start was to leave a battery charger hooked up & crank up the amps.
sounds like with your mods that bike should be quick, good luck.
btw, the hotrod crank is a shortrod 66.3mm stroke

[SandTrix]

i would fatten the needle a bit...on my 450R with a lectron if it were lean it would not start.

[cockeyed racing]

SandTrix, on 05 March 2010 - 07:40 AM, said:

i would fatten the needle a bit...on my 450R with a lectron if it were lean it would not start.

[cockeyed racing]

Fatten the metering rod 1&1/4turns to achieve good idle it dosent wander when returning to idle.this carb was set up by packard eng @51.8 & 3/4 rich would this uncommon or just what the motor likes?Still needs help from charger but runs great once started,can get 1or2 starts before hooking charger.can't test ride untill I get drag axle hope today

[Kawiking]

do they make a aftermarket decompressor button for the yfz, like the ones bob craycraft uses on the big raptor 660 based motors ? i know john has one on his craycraft raptor, austin oneal also runs them on his.....

[Kawiking]

http://forums.atvdra...347

[dylan]

i dont think u need any kind of manual decompressor. a motor that small w/out much compression shouldnt have a problem starting. i'd bet the problem is valve clearance or timing.