CRF kick start resistance increased ... why?

[Nestrick]

I am a 56 year old who started riding last year to spend more time with my teenage son ... I am 180 lbs, 6' tall and of average strength ... facts that will become pertinant later.

Purchased a new 02 CRF-450R in June of last year and had it modified to make it more amenable to Michigan trails which are mostly sand and mud [see list at end of post]. Being considerably anal but not extremely mechanical, I maintained the bike scrupulously with regard to cleanliness, air filter maintenance, chain tension & cleanliness, engine & transmission oil changes, and general lubrication of the moving external parts. After approximately 200 hrs operation the bike suddenly wouldn't start ... the local Honda dealer explained that the valves [intake only] were 'closed' due the fact that I did not monitor and properly adjust the lash with appropriately sized shims. They managed to reshim them and told me to monitor them at least every 30 hrs operating time thereafter. After approximately 25 hrs additional run time the bike again would not start and a check of the lash indicated they were totally closed again. This time they replaced both intake valves with brand new Titanium ones, rebuilt the top end with new piston, rings & associated components and told me to continue the valve lash monitoring routine every 15 hrs or so. Because this situation appeared to be worsening, and runtime seemed to be an extremely critical data point, I installed a SenDec motor meter to accurately keep track of the run time. A check of the valves at 10 hrs showed no change in valve lash from spec ... however at 21 hrs both intakes were down 0.003" so I purchased appropriate shims to reset to factory spec. At 30 hrs runtime a check indicated both intakes to be down 0.005" [essentially closed again] ... so I returned to the Honda dealer for help. They said that Honda believed this problem to be due to dirt intake into the engine and that I needed to replace both the head and the valves which would cure the problem ... because this seemed extemely expensive and likely to result in the same problem again if dirt really was the problem ... I began researching and found this site and the answers posted herein.

I'm still not out the woods yet though, as my dealer again spoke with Honda and they did indicate that installation of steel valves would not jeopardize the bike's longevity or performance characteristics but they did not inform the dealer that different springs would be needed for the steel valves ... so they installed standard Honda springs with my new Kibblewhite valves [by the way all four valves were changed at this time at the suggestion of the dealler ... also rebuilt the top end again with new piston, rings, etc].

On getting my bike back, the dealer noted that the engine is now very noisy [internal noise from the top end of the motor ... not present before latest work] and the resistance against the kick starter is now dramatically increased. It is at this point that I took my Honda dealer the data posted herein regarding CRF valve problems, along with the MXOffroad.com Project CRF-450 article regarding installation of the complete Kibblewhite kit and had them read the information. Next I had them order the appropriate valve spring kit from Kibblewhite and it the engine will be torn down again to replace these components.

What bothers me the most about all this trouble is that I love riding my CRF ... it is the perfect "old man's" bike ... relatively light, hugely powerful to meet any demand and not difficult to ride by those possessing less than professional skills. However, at this point in the story, the modifications done to correct the valve problems have resulted in a dramatic increase in the kick start resistance ... to the point that I cannot kick through with sufficient intensity to start the motor reliably. Up to this point I have easily been sufficiently strong to kick the bike with no problems ... I have over 250 hrs riding time, mostly by myself, and have never had trouble kicking through the start cycle until now.

Of course, my Honda dealer can start the bike with no problem [naturally, he's a big guy pushing 230 lbs or so] and they look at me like I'm getting senile or in need of a Bow Flex ...

Well, if anyone has spent the time to read through this 'horror' story ... I'm looking for some opinions and advice. I put more than 2 K-bucks into this bike when it was new upgrading and altering the componentry to make it a worthy trail bike for Michigan conditions with the thought that I would get several years enjoyment out of it before wearing out the motor or some other important and expensive part. Now this dream doesn't seem to hold much water ...

Considering that similar valve changes and piston/ring changes in the past did not alter the kick start resistance ... why has it changed so dramatically now?

I am not expecting the kick start resistance to change much once the proper Kibblewihite vavle spring kit is installed ... right?

Is it possible the decompression lobe on the cam is not functioning correctly and is causing the loud top end noise as well as the increase in kick start resistance?

Anything else that I might look into regarding the kick start resistance and ways to reduce it back to normal?

Thanks in advance for any help that folks might lend to me on this matter. Please don't think I am complaining about my Honda dealer ... they have sold less than ten CRF-450s since they came out in 2002 and all but mine were to motocrossers who race them and more importantly, do their own engine work ... hence the dealer never sees them except for ordering parts occasionally. I am their best service customer with a CRF-450 and they're cutting me considerable slack with regard to service charges for the work as they really have no experience.

Terry Nestrick

2002 CRF-450R
Scott's triple clamp/Pro-Taper bars/steering stabilizer combo
Scott's Shark Fin
Scott's modified forks/shock/springs for 200 lb rider off road
Works Connection Pro-Perch adj Clutch with Hot Start lever
Arc brake lever assembly
Moose bark buster hand guards
Regina O-ring chain
Renthal 52 tooth rear sproket
BRP billet chain guide
PC Racing Air Filter housing kit
Twin Air Filters & Blue filter oil
ZipTy Fuel Mixture adj screw
BRP spark arrestor muffler cap for stock exhaust
CEET tall form foam with gripper seat cover
Works Connection radiator/shroud braces
Works Connection enduro skid plate

 

[Hick]

Originally posted by Nestrick
However, at this point in the story, the modifications done to correct the valve problems have resulted in a dramatic increase in the kick start resistance ... to the point that I cannot kick through with sufficient intensity to start the motor reliably. Up to this point I have easily been sufficiently strong to kick the bike with no problems ... I have over 250 hrs riding time, mostly by myself, and have never had trouble kicking through the start cycle until now.


Is it possible the decompression lobe on the cam is not functioning correctly and is causing the loud top end noise as well as the increase in kick start resistance?

If the clearance on the decompressor is set too high it will be too hard to kick over, the decompressor wont be actuating enough. Set too loose and it will become too hard to start because it won't build any compression...

This can be checked relatively quickly. Check your manual and see what your decompressor clearance is...


Hope this helps.

 

[Hick]

Replace where I said "set too loose" with "too little clearance."


Thanks.

 

[Rich Rohrich]

Originally posted by Nestrick
I am not expecting the kick start resistance to change much once the proper Kibblewihite vavle spring kit is installed ... right?

Correct. It should not change at all from a properly functioning stocker.

Originally posted by Nestrick

Is it possible the decompression lobe on the cam is not functioning correctly and is causing the loud top end noise as well as the increase in kick start resistance?

That would be a reasonable conclusion to draw, and a good place to start. If you pull the spark plug out and the resistance is gone, then it's very likely the compression release is not functioning properly. If it's still hard to cycle through then it's probably some mechanical issue .

Originally posted by Nestrick

I am their best service customer with a CRF-450 and they're cutting me considerable slack with regard to service charges for the work as they really have no experience.

This could very well be the root of the problem. It sounds like they are just having trouble assembling the engine properly. This is a VERY easy engine to work on so that's fairly troubling. Good luck.

 

[DEANSFASTWAY]

Hi Rich , Hi Nestrick : I really hope this is not youre problem but it could be . If the intake and exhaust springs are swapped into the wrong places the longer springs could coil bind and cause valve noises and much much more parasitic mechanical drag than if they are properly installed and may drop and hit the piston.. The exhaust valve springs are about 10mms longer than the intake springs which are designed shorter since they sit under a bucket lifter assy. I think the stock intake springs have a white paint stripe on them and the exhausts have blue paint or something like that.If this is the case though you probably would have dropped a valve the first time you rode the bike . To be safe Id have someone in the know check it out further . Actually the first time I had one apart I mixed up the springs and didnt notice it until reassembly . Not to mock the guys at the Honda dealer because I know its hard to work on Goldwings and adjust valves on 929s 954s and stuff,those bigger four cyls have 16 valves and you can hardly see them let alone pull up the cams and swap shims, I know Ive been there. Well, maybe they just overlooked it Warranty work new bike preps and problems and stuff Id make sure If I were you my friend . You might just have a maladjusted decomp lever like others said though.You know almost every time I get involved with a tired CRF or one with tight valves the customer has already installed a new piston kit and usually doesnt understand the valve adjustment deal.Usually the last bike they owned they mixed gas and didnt have valves.With stiffer valve springs correctly installed there may be a hint more resistance to rotation but the amount would be negligible espescially on a single cyl ,I doubt anyone could ever feel it by hand maybe like turning with an inch pound torque wrench or something .But i bet if there were HD springs in the wrong spots it could cause a shakeup . Good Luck and let us know what you find out. DEAN

 

[DEANSFASTWAY]

On a sidenote Id like to say that the Kibblewhite products are good stuff . I must have installed about 100 sets of TRX XR400 springs in the last three or four years and NEVER had an issue with them. Ive seen some other brand valve springs on other shops built GSXR liquid cooled drag motors where there springs were so tight you needed a deisel battery to crank the motor over and thats after the plugs were pulled .This unwarranted drag saps power. The motors were built by a big name Superbike shop who shall remain nameless They should have been on a big block chevy .We were worried about breaking the cams so we swapped them out for some looser springs and probably freed up some power. The bikes ran good but the owner ran out of $$$ and soldout .Nestrick it might not be a good idea to run HD springs with the Ti Valves because of risk of pull through or excessive wear on the valve face or keeper slippage. The Ti valves are softer than the stainless intended valves ,maybe Mike Perry or SFO or RICH might have some thoughts on this.Ive seen some 250F Ti valves where the valves almost looked like giant roofing nails The kids were push starting the bike for awhile after they got tight. Maybe I can send pics to Rich and he can post .

 

[MXN4FUN]

Check to make sure the dealer didn't advance the cam timing by mistake. I inadvertantly advanced mine by a tooth and experienced more difficulty in kicking it over. It still started and ran but as soon as I set it back it started and kicked over like it should.

 

[Nestrick]

Thanks to all for the help, suggestions, advice and support in my quest to resolve the "dreaded intake valve" problems on my CRF which were compounded by strange new motor noises and increased kick starting resistance following initial repair work.

As previously stated, I ordered the complete Kibblewhite valve spring kit to replace the Honda components that my dealer used to install my new Kibblewhite stainless steel valves [both intake & exhaust]. [By the way, my dealer installed the Honda valve spring components based on cost ... the Honda parts were considerably cheaper ... without knowing different, this reason made the decision seem OK & he didn't inform me until after the installation was complete.] When these arrived this Monday, we talked strategy based on the info contained in your replies to my query. During engine tear down, we removed the plug to test the resistance to turning the engine over via the kick start and did notice reduced effort necessary. Hence when the cam was removed to permit access to the valve springs, seats, retainer & cotters, we disassembled it to carefully inspect the decompression cam assembly and found nothing wrong. Upon removal of the Honda springs we found the intake and exhaust units to be the correct species for each location and each was installed in the correct direction ... again nothing appeared to be wrong. However, on installation of the Kibblewhite components, the mechanic did notice that the Honda cotters permitted the shims to rock considerably more than the Kibblewhite units ... arguably a potential source of the top end noise we had noted previously. Reassembly of the entire valve train with all of the new Kibblewhite valve spring kit components did not result in the need for any change in shims to achieve appropriate valve lash for either the intakes or the exhausts. On complete reassembly the engine started immediately ... the noise level is noticeably reduced ... the resistance to kick starting is still much higher than originally, but is somewhat improved [reduced]. Prior to complete disassembly, we also found the decompression lifter lash to be the appropriate 0.014" setting and the cam sproket timing marks to be in the appropriate locations for normal operation [not advanced or retarded a tooth].

At this point my dealer taught me how to start the bike 'the old fashioned 4-stroke way' ... seems that up to now, I had always climbed on and simply kicked the bike through without any attention to where in the 4-stroke engine cycle I was. As you folks all likely know, kick the bike until it reaches the point of maximum compression, then kick very slightly past this point, allow the kick starter to return to the top of its cycle, then vigorously kick the bike. This allows the decompression circuit to work getting me past top dead center, after which I can now easily kick through the cycle despite increased resistance in the motor. If I do not follow this procedure at the moment, I simply cannot get sufficient 'power' on the kick to spin the motor fast enough to start reliably ... but with the procedure described, I can easily start the bike on the first kick from dead cold [all right it was in the 80's here today].

Best guess on the new engine noise:
* The stainless valves are heavier and their contact with the valve seats may lead to louder, different frequency, sound eminations ... my bike is definitely louder [regarding upper engine noise in the area of the head] than a stock 03 CRF-450R with ~30 hrs operation time on it that was in the shop today ...
* The Kibblewhite valve spring kit components [at least the cotters] for the intakes seemed to allow less rock of the shims due to tighter fit in the retainers ... perhaps the Honda cotters for Titanium valves are very slightly different in dimension than those of Kibblewhite for the stainless steel valves? Interestingly though, on final assembly we were able to use the exact same shim in each valve to achieve the correct lash following installation of the Kibblewhite valve spring kit. Rocking of the shim might be a source for the upper engine noise?

Best guess on the increase in kick start resistance:
* In one operation, we cut all four valve seats, properly lapped all four new stainless steel valves into each seat, and we rebuilt the top end with a new piston, rings and associated components. These changes likely increased the compression of the engine compared to my original state where both Titanium intakes were essentially closed and on removal, both steel Honda exhaust valves were showing cupping on the edges of the valves despite maintaining the correct lash of 0.011". Even with the automatic decompression circuit functioning, the engine is sealed better now and the new rilngs are yet to be broken in and seated properly. Maybe these changes result in the increased resistance to turning the motor over?
* One thing is for sure, we could not find anything else wrong in the cylinder or head assemblies to account for a mechanical issue resulting in increased difficulty kicking the motor ... the motor appears to be assembled properly, with all components meeting appropriate Honda spec's and torques.
* I need to follow the stated 'routine' for starting the engine, but I can readily do so now.

It's out to the trails tomorrow for a break-in ride, then some additional use to put some time on the motor. The dealer mechanic feels that some hours on the motor will free it up to spin easier ... guess we'll just have to wait and see. In the mean time, testing runs in my back yard indicate that my motor had definitely become 'tired' ... the low end torque is back in strength and the the rev is much snappier now. Can't wait to see how it feels out in the woods.

Thanks again to all ... hope this info is useful to others.

terry nestrick

 

[MikeyG]

Try lowering your idle a bit. This happened to someone with a YZf, did you ever raise it too counteract the bike not starting maybe?