Topic: Noob buys first bike... wants to build cafe racer

[scottly]

I think he’s working abroad on a large project for a few more weeks..

What makes you think that?

[xanaphyst]

It seems like the engine is getting hot and locking up. 

Can you plz be more specific on the "locking up"?   Does the motor just stop running?  Or does it not want to start back up after turning off?  Will it kick over?

Typically, if a motor "locks up" it has sustained a major mechanical malfunction. And if riding, it could cause the rear wheel to abruptly stop and cause a skid. Doesnt sound like this has happened.

, it could cause the rear wheel to abruptly stop and cause a skid.

Yes that is exactly what is happening ...... just like my other bike that had a clogged up oil intake.  Exact same thing except this engine is rebuilt 100% by Hondaman so I'm not sure what to do

[xanaphyst]

I think he’s working abroad on a large project for a few more weeks..

What makes you think that?

Yes I was overseas for work.

I need to take the top cover off and see if its getting oil up there. I'm thinking the cam is locking up due to low oil pressure.

My bike does not have a low oil pressure light as I have not installed that digital dashboard thing from cognito moto yet.

[scottly]

Well in the end it took a bit longer than I expected but its pretty much all done now......even have a title !!!!   Last bit is to tune the new VN34 4-2 carbs and then get it registered. It ran pretty good with the stock carbs but not having the factory airbox really restricted their operation.

It seems like the engine is getting hot and locking up.

And from a different thread:
"My bike runs well from idle to about 60% but not so great at all after that and if I run it hard the engine gets very hot. It appears my jets are 165. Anyone have an idea what jets are in there VM34 carbs?"
What do the spark plugs look like? After it cools off does the motor turn freely? The motor may be "soft seizing" due to getting too hot along with tight piston-to-cylinder clearances. 

[piefairy]

I'm a complete noob when it comes to fixing these bikes, but I had a similar sensation due to a loose chain. It would bind up and feel like the rear wheel was binding, dragging. Doubt its your issue, but worth a second look.

[xanaphyst]

Well in the end it took a bit longer than I expected but its pretty much all done now......even have a title !!!!   Last bit is to tune the new VN34 4-2 carbs and then get it registered. It ran pretty good with the stock carbs but not having the factory airbox really restricted their operation.

It seems like the engine is getting hot and locking up.

And from a different thread:
"My bike runs well from idle to about 60% but not so great at all after that and if I run it hard the engine gets very hot. It appears my jets are 165. Anyone have an idea what jets are in there VM34 carbs?"
What do the spark plugs look like? After it cools off does the motor turn freely? The motor may be "soft seizing" due to getting too hot along with tight piston-to-cylinder clearances.

I've now tried different jets and different types of carbs. The trottle responses and what not change but the temporary lock up thing still happens all the same.

[scottly]

Is the "lock up" strictly temperature related, and always frees up after cooling off?

[xanaphyst]

Is the "lock up" strictly temperature related, and always frees up after cooling off?

I should probably clarify that I originally thought it was heat related. I dont think its heat related anymore. I think its oil related.

The original reason I said heat related is because I would have never thought about oil pressure being the problem.


The symptom is as follows: If I go real easy the bike will remain running. If I start riding harder and more RPMS the rear wheel locks up ...engine wont kick over for a minute. Then it frees up. 

[MauiK3]

I would think that by now it would be pretty seized up and not start at all. You may be looking at ill fitting pistons or something similar, not bearing related, they seldom recover from this type of problem.

[jonda500]

I would take a guess that the oil supply to the camshaft journals is insufficient for some reason (blockage?) causing the camshaft to temporarily seize. My Datsun engine did this when a little piece of rag was left (pushed into the hole by the head surfacing shop) blocking the oil supply passage.
John

[scottly]

The symptom is as follows: If I go real easy the bike will remain running. If I start riding harder and more RPMS the rear wheel locks up ...engine wont kick over for a minute. Then it frees up.

This is exactly what happens when an engine soft-seizes from the piston-to-cylinder clearances becoming too small as the engine heats up under increased load. The aluminum pistons expand more than the iron cylinder, so if the clearance is small to begin with, it gets smaller with heat, to the point of seizure. Then, after the piston cools off and contracts, the engine frees up.
An oil supply failure would happen regardless of load, and cause permanent damage to the cam and related parts: it wouldn't just free back up after a short cooling off.