Motorcycle Repair: Honda C70 suspension, honda c70, lean mixture

Question
QUESTION: Hi,

I have a 70's Honda C70 (chassis number in the 3,000,000's) and is loses power going up hills. The engine tries to die on steeper ones.

It has a trial bike carb pz19 carb, the points gap is good and the spark plug looks new (running a bit rich I think). The carb is facing backwards due to the manifold being reversed, I will probably modify it back to the correct direction.

The hills are not that steep but the bike has to be pushed by my feet to get over a brow unless I have a run up.

Any ideas? It starts really really easy with a kick so compression seems good, not a lot of resistance though with the kick start pedal.

Any help appreciated.

Thanks
Keith

ANSWER: Keith, there are three things that can result in a lack of power you describe.  Start first with a compression check. If the compression is much lower than 140 psi, you may be looking at a top end overhaul. Next, check the timing with a timing light. Be sure the timing is advancing to the full advance marks on the flywheel.  The last thing is the fuel mixture.  An overly rich or lean mixture can cause a lack of power. The carb needs to be clean and the floats properly adjusted.

Regards
Rich



---------- FOLLOW-UP ----------

QUESTION: Hi Rich,

Me again, can you advise on the engines that I could fit to this frame without modifications please.

Rgds

Keith

ANSWER: Keith, I think you'll find any 70 engine will fit in without modification.  

Regards
Rich

---------- FOLLOW-UP ----------

QUESTION: Hi rick,

me again. I took off the front wheel of my bike to take offthe front mudgauard. When I put the wheel back on and toomk the bike for  aride the front suspension went very soft. The wheel travels up an down by about 3 to 4 inches and is very very soft. Dio i need new supsension units or can they be repaired? It seem strage that it happened after wheel removal, I checked it twice to see if i have fitted the wheel on wrong. Any advice welcome.

Thanks
keith

Answer
Keith, there's not much in the way of suspension on those little bikes.  There's just a couple of springs and shock absorbers. If the shocks are replaced in the right locations there's not much else that can go wrong.

Sorry, I can't help more.

Rich