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Discussion Starter · #1 ·
OK, here is my problem. 450 got hard to impossible to start when it was cold, but would start easy when it was warmed up. so we checked carb and it was fine, checked spark and it was good. next we checked the valves and decomp. exhaust valves are within spec but the intake valves are so tight you cant get even a 2 thousanths feeler in there. now im not an expert on this, but why would valves tighten up? shouldnt they get looser? Oh, and its an 06 450er with stock motor.

HELP!!
 

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Discussion Starter · #2 ·
And you can crank it over and it will spit alittle blue flame out the exhaust every few turns. any help would really be a lifesaver.
 

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Thats just the nature of the R. Mine had the same exact symptoms as you have . I scratched my head for a while then decided to adjust the valves. Opened it up and the intake valves were too tight. I adjusted them and the starting problem and popping went away. With your bike at idle it may hesitate at in a transition to wide open throttle as well. All of it should return to normal once you adjust the valves.:sweatingbullets:
 

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Discussion Starter · #5 ·
i just talked to the previous owner and he said that he never adjusted them. so, im tight on both intake valves. one is 60 thousanths and one is 62 thousanths. anyone good at math and metric conversions?
 

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Discussion Starter · #6 ·
also, isnt it strange that the exhaust valves were in spec and the intake valves are tight?
 

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Discussion Starter · #8 ·
just bought the whole shim kit! 141 shims! it will live again!
 

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i just talked to the previous owner and he said that he never adjusted them. so, im tight on both intake valves. one is 60 thousanths and one is 62 thousanths. anyone good at math and metric conversions?
Im sure your talking about the shim thickness, anyways what did the exhaust valves clearance measure at (you said they were within specs)? On my 04 TRX450 the intake valves should be .060 clearance, the exhaust .11. This seems really loose but I recently did this too. I didnt use calculations, I used a michrometer and measured the shim thickness and made an educational guess at picking them out for the right shims.

Some four strokes loosen up and you can hear it ticking(like 400EX's, they adjustable valves) but shim under bucket engines tend to tighten up and this tends to make them hard to start. Typically, if an engine has a lot of time and the valves need adjustment, its close to needing a valve job because the valve seats are wore out.
 

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the stock titanium intake valves will suck into the head, keep the air cleaner maintained and they will last longer

when its too tight to shim into spec. its time for a valve job
(and probably a piston by then also)

but if your getting a valve job you might as well get it ported/polished
 

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Discussion Starter · #11 ·
Im sure your talking about the shim thickness, anyways what did the exhaust valves clearance measure at (you said they were within specs)? On my 04 TRX450 the intake valves should be .060 clearance, the exhaust .11. This seems really loose but I recently did this too. I didnt use calculations, I used a michrometer and measured the shim thickness and made an educational guess at picking them out for the right shims.

Some four strokes loosen up and you can hear it ticking(like 400EX's, they adjustable valves) but shim under bucket engines tend to tighten up and this tends to make them hard to start. Typically, if an engine has a lot of time and the valves need adjustment, its close to needing a valve job because the valve seats are wore out.
yeah, i was talking about shim thickness. i have room to re-shim them this time and maybe one more. hope it last through the summer and i can do a rebuild over the winter. if not, i will be trying to put the crf head on it.
 

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Discussion Starter · #13 ·
it sucks to have to do this kinda stuff right after i sold my 400ex, so now i have nothing to ride until i fix it and its 85 degrees out!!
 

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great site. i reviewed Ghott's "how-to" on the valve adjust and it helps clarify a few things. ghott did a fantastic step-by-step write up.

this topic is also very good and bang-on to my problem: I have 13-14 thou clearance on exh, but intake shows no clearance. smallest feeler I have is .0015 (like paper), and I can't squeeze that in there.

so what to do for shims? maybe rolll the dice on intake shims that are 7 thou thinner than what I have in there now?

also sounds like it may be getting close to needing valve job???????? or maybe previous owner never checked clearances, ever. for now, i want to see what I can get.

can you just loosen off cam chain tension to wiggle the chain off to get cam out, or do you need to remove the cam bolts, etc....? I know my rhino says to basically disassemble the cam, but you can get away with taking tension off and pulling chain off cam.
 

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FWIW, i was able to slack off chain tension by turning in screw, then I wiggled chain off cam timing gear. never had to remove the gear. took out complete cam with gear still attached. still used a zip tie to hold up chain tho.

I had 160 shims and replaced with 135 and a 140.
 

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yep. my timing is bang on. funny, i was just looking at your website when you posted!! I was looking for your throttle switch bypass. I found another one from OTMTRX. But from what I read, these switches should not cause no spark.
 

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Best way to do it so you dont mess up timing is to zip tie the gear to the chain and remove the gear from the cam. Also make sure you stuff rags in the hole this will do 2 things. 1 stop any bolt from falling down there ( which makes for a bad day) and 2 it keeps the chain from falling off the crank bye keeping some tension down there. dont short cut steps your only gonna make a easy job harder.
 

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not sure how I made the job harder, or had any more or less risk of being off on my timing. the crank mark is bang on, the gear is still on cam, and the gear line and index mark are both still lined up perfectly.

I completely agree on the rag... I rebuilt my son's DOHC KTM 450 sxf. I couldn't find one valve shim... I wouldn't put it together until I found the shim clear across my shop floor several days later. if you drop a shim in motor, it is a major PITA to get it out.
 

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I'm having the same problem. Bought the Quad and it ran but would not idle. Had my friend take it apart cleaned the Carb and jets they are spotless. Next we took apart the valve cover reshimmed the Valves as the intake Valve was really tight and now they are within spec but the intake in very slightly loose. When I crank it over it gets compression sometimes as it pops and starts for 1-2 seconds and sometimes it does nothing but crank the starter. We double checked the timing and its spot on. The engine is getting Fuel ,Air and Spark so at this point I'm kinda at a stand still. Could it be a PCM problem or something like that

adjusting the idle screw and choke also do not help

Next thing to do I guess is compression test and leakdown and or remove the Head?
 
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