Topic: Need some engine advice

[Cevan]

I bought this F1 a few years back with 46,000 miles and got it running.  I rode it up and down my driveway and shifted thru the gears and that’s about it.  Compression numbers were low and having no info on prior rebuilds or maintenance, I figured I’d pull the head and check the valves.  I’ve got Hondaman’s book on the way.  The bike is completely stripped down at this point.  Engine-wise, I’m looking for just stock power output and reliability.

At least three of the valve guides are out of spec so it looks like I’ll need valve guides.  Can I reuse the valves?  One of them looks a little pitted where the adjuster makes contact with it.  I think this one needs replacing at a minimum.  Do new valve guides necessitate having new seats cut? 

I’ve yet to measure the cylinder bores but there is a noticeable step at the top.  So either a hone and re-ring or a first overbore.  Am I on the right track here, once I have measurements?

The cam lobes measured within spec so is there any reason I can't reuse it? 

I’ve attached pictures of the cam tensioner parts.  The chain doesn’t appear to have any defects but should I just replace all these parts anyways?

I also don’t know if I need to split the case.  The engine did seem to run nicely.  Splitting the case would allow me to use an endless chain as opposed to one with a master link and inspect the internals, right? 

[Cevan]

Here are a few more:

[rtbmrgl]

I bought this F1 a few years back with 46,000 miles and got it running.  I rode it up and down my driveway and shifted thru the gears and that’s about it.  Compression numbers were low and having no info on prior rebuilds or maintenance, I figured I’d pull the head and check the valves.  I’ve got Hondaman’s book on the way.  The bike is completely stripped down at this point.  Engine-wise, I’m looking for just stock power output and reliability.

At least three of the valve guides are out of spec so it looks like I’ll need valve guides.  Can I reuse the valves?  One of them looks a little pitted where the adjuster makes contact with it.  I think this one needs replacing at a minimum.  Do new valve guides necessitate having new seats cut? 

I’ve yet to measure the cylinder bores but there is a noticeable step at the top.  So either a hone and re-ring or a first overbore.  Am I on the right track here, once I have measurements?

The cam lobes measured within spec so is there any reason I can't reuse it? 

I’ve attached pictures of the cam tensioner parts.  The chain doesn’t appear to have any defects but should I just replace all these parts anyways?

I also don’t know if I need to split the case.  The engine did seem to run nicely.  Splitting the case would allow me to use an endless chain as opposed to one with a master link and inspect the internals, right? 

Hello Cevan,
 First of all your in good hands here, there are a lot of sharp guys with a bunch on experience, much more than me.
Just for starters if it were mine I would be replacing guides and valves and cutting new seats. One or two sizes over-bore, cam chain and guides. If it shifted ok you could probably not split the case, but I think with the miles maybe it would be a good idea.

[Cevan]

Hello Cevan,
 First of all your in good hands here, there are a lot of sharp guys with a bunch on experience, much more than me.
Just for starters if it were mine I would be replacing guides and valves and cutting new seats. One or two sizes over-bore, cam chain and guides. If it shifted ok you could probably not split the case, but I think with the miles maybe it would be a good idea.

So split the case to do a general inspection?

[martin99]

Now lets see...

You need to have the seats recut if you are installing new guides. The valves are used to a bit of slop in the old guides. The new guides will have a tighter tolerance and the valve will not sit perpendicular in the seat without recutting.

Whether or not you replace the valves depends on wear. Some pics may help here.

I would replace the tensioner blade and roller. They may not look too worn but could be brittle after 35yrs of service. If you want to go the extra mile and split the cases probably not a bad thing - but be aware the cost of the rebuild will go up exponentially with every part you remove/uncover. Primary chain, seals may also want attention after 46K. Becomes kind of addictive to have everything right. If your camchain already has a master link, I think that's a clue that someone's already done some engine work. Pretty sure they are endless as standard.

Measure the bores and if in spec you may well get by with rings and a hone. It's not unusual to have a step at the top of the bore, but obviously the more pronounced this is the more likely you will need to rebore. If the cam is within spec I would re-use it.

You sound like you know what you're doing anyway

[Cevan]

Just a clarification: the cam chain currently in the engine has no master link.  The cylinders have never been bored.

[thirsty 1]

One more thing to think about is how much do you plan to ride the bike? Sunday cruiser or everyday rider? If it's just a fun bike then I'd be more inclined to let things slip by. If it's going to be a work bike then you might want to dig a little deeper into it. The Cam is in spec so use it. Guides, chains, and tensioners should be replaced as they are a maintenance item. I'm thinking the head should be gone through to with that mileage but well again it depends on what your going to use the bike for.

[lucky]

It is not the miles. It is all the years!

Replace the cam chain. The early ones were prone to failure.
Replace the cam chain rollers and make sure to check the crank oil galleries for debris!!
Put in new valve guides. Hone them to fit the new valves if needed.
Re cut the seats. Install new springs.
bore the cylinders and hone them to fit the new pistons.
Watch this video about seat cutting.
http://www.youtube.com/watch?v=QIVj_L1akl4