So i bought a TB race head kit for my bike a while ago. Right after i got it i installed it myself and installed the timing sprocket one tooth off. It ran decent for a while, no top end what so ever, until one time i was coming up into my steep drive way and let of the gas. Bike rolled back and hit the bumper of the car behind me, kinda lurched, then died completey. It wouldnt start at all after a kick or two and then, on the third or forth kick, i bent a valve and the kick starter hit a brick wall of resistance. Took it to a local shop and they confirmed everything i have just said and replaced the valve. Even after they replaced it and aligned the cam to TDC, they still couldnt get it to run decent at all, still had no top end, no matter what different jettings and settings they tried. What do yall think could causes the kit to not work like crap like it has for me? Everyone reviews the TB kits excellently, so i cant imagine its really a flaw in the kit. What do you think? Also, what kind of motor shop would i be best with going to to have this thing fixed (i just dont want to screw it up anymore myself)? Our trusted motorcycle mechanic couldnt figure it out, but then again his forte is street bikes. Would i be best off with a small engine shop?
Dead TB
whatme
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So i bought a TB race head kit for my bike a while ago. Right after i got it i installed it myself and installed the timing sprocket one tooth off. It ran decent for a while, no top end what so ever, until one time i was coming up into my steep drive way and let of the gas. Bike rolled back and hit the bumper of the car behind me, kinda lurched, then died completey. It wouldnt start at all after a kick or two and then, on the third or forth kick, i bent a valve and the kick starter hit a brick wall of resistance. Took it to a local shop and they confirmed everything i have just said and replaced the valve. Even after they replaced it and aligned the cam to TDC, they still couldnt get it to run decent at all, still had no top end, no matter what different jettings and settings they tried. What do yall think could causes the kit to not work like crap like it has for me? Everyone reviews the TB kits excellently, so i cant imagine its really a flaw in the kit. What do you think? Also, what kind of motor shop would i be best with going to to have this thing fixed (i just dont want to screw it up anymore myself)? Our trusted motorcycle mechanic couldnt figure it out, but then again his forte is street bikes. Would i be best off with a small engine shop?
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948 Posts
i had the same problem that i thought it was carb jetting i set the timing at perfect location at flywheel and timing gear dead on ran like crap so for ****z and giggles i retarded it one tooth and that was the perfect spot it ran perfect then when i took the cover back off it was aligned up right again dont know waht the problem was but now it is just (looks like 1/2 tooth off TDC bottom of notch) and it runs perfect did that to 2 difrent honda engines one with 117tb with hace head and one with 88+r
tripple check your timing. 0 on cam gear at 9 o clock and flywheel T lined up with notch on the case. when you think youve got it set turn the flywheel 2 revolutions and re check it. once you get the timing set jet it, sounds like the valve may have become brittle from the bike running lean. your mechanic should now how to set the timing on a single cylinder 4 stroke if hes working on street bikes.
The thing is ive reset the timing atleast 3 times. Ive set it dead on, to where the mark on the cam gear looks a 1/2 tooth high and to where the mark looks a 1/2 tooth low. The shop we went to does great work, and has helped us out on lots of other projects on our sport and dirt bikes, hes one of the best guys in town. He said they reset the timing twice just to make sure they got it right. Also, i highly doubt its the jetting since he spent 2 1/2 hours working on jetting it correctly one day. He thinks the kit is just crap. Any other suggestions?
and it HAD alot of compression. I worked on it last night, set the timing so that the O on the cam sprocket looked 1/2-1 tooth low of where it should be. Kicked it over a few times, heard a clicking noise once or twice, and now it has no compression. The rockers still feel tight against both valves, so i dont know that one of them is bent, but thats what im thinking just happened. It now feels like its somewhere in between the compression it had when it ran and the lack of compression it has when you remove the sparkplug and kick it.
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3,869 Posts
You just bent the valve again.
Well, i just went back out and put the timing back to where it was (to where the O on the cam sprocket is slightly above the mark on the heads), and i can get it to run, but just barely. Would it be able to run at all if i bent the valve? Because its running worse now than it was before i started screwing with the timing (if thats even possible). Another thing i noticed is that it is impossible to have the timing dead on. The O on the sprocket always appears to be a half tooth high or a half tooth low on the cam chain, never actualy perfect. Could i have somehow sheared the woodruff key during this whole ordeal, and that would actualy be whats wrong? Or is that slight difference normal?
where r u located. if your anywhere near ohio I will help you fix it. I am sure someone on the board would be more than willing to help you with your problem. I hate to speak on behalf of the others but I remember how frustrating it was at first when building these. just trying to help you out.
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948 Posts
Thats what i was talking about with both my engines make it 1/2 tooth below the 0 on the cam chain that is where mine are and they wont run any other way
I live in Springfield Missouri.
B&N- How do you mean? Where the O on the sprocket appears to be a half tooth above the mark?
Well then, if timing isnt the problem, what could it be? Is there anything that could have gotten screwed up when i bent the valve the first time?
Also, again, Can the bike run at all if the valve is just slightly bent? As i said, the bike runs, but just barely. Do you think the valve is actualy bent now?
B&N- How do you mean? Where the O on the sprocket appears to be a half tooth above the mark?
Well then, if timing isnt the problem, what could it be? Is there anything that could have gotten screwed up when i bent the valve the first time?
Also, again, Can the bike run at all if the valve is just slightly bent? As i said, the bike runs, but just barely. Do you think the valve is actualy bent now?
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948 Posts
best bet is to take off he head and look at the valves and seats you might have a broken spring ive breok 2 and Hackmunch as broke several the bike will run but not real good. Do you have compression, is it good or not?
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948 Posts
i look at my timing mark on the cam it is a 1/2 tooth below the notch on the head i have it like that on 2 of my engines and deadcenter on a couple other stock ones i dont get it but the 2 engines one has a tb 54mm cylinder and the other has a 52mm Tak cylinderwhatme said:
thats what i was thinking.
I screwed around with it some more and it started running differently again. I just took the carb off and put it back on, no jetting changes, though a whole bunch of gas spilled out when i left it upside down by accident. Run decent at idle, but as soon as it gets any higher than idle it pops and backfires like hell. The back fires scare the **** out of me too because you can hear the pipe ping right by where it comes out of the heads. Sounds like the damn thing is gonna explode and throw burning hot shratnel into my leg.
Anyways, do you think that with all of what happened there would be any point that the key would be sheared?
I screwed around with it some more and it started running differently again. I just took the carb off and put it back on, no jetting changes, though a whole bunch of gas spilled out when i left it upside down by accident. Run decent at idle, but as soon as it gets any higher than idle it pops and backfires like hell. The back fires scare the **** out of me too because you can hear the pipe ping right by where it comes out of the heads. Sounds like the damn thing is gonna explode and throw burning hot shratnel into my leg.
Anyways, do you think that with all of what happened there would be any point that the key would be sheared?
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