VF500F Piston/Rod removal

I just bought a total restoration project 86 VF500F with an 85 engine in it. Unfortunately the compression is 60 PSI on the rear cylinders and 85 PSI on the fronts. Looks like a ring job is in order. My question (not clear in the Honda Helms manual) is can the piston/rod assemblies be removed without splitting the cases? I understand that the heads have to be removed. It appears that you can remove the oil pan to get to the big end bolts.

Thanks for any help! Jim from Houston

 

My advice would be to forget it.
The rings could just be gummed up and the fact they are all similar suggests a possible flawed measurement technique. However, if the readings are genuine and the engine is badly worn then by far the best/cheapest option is to try to find a decent 86 engine.

 

like those are quite common ?

no chance for a decent rebuild without having new parts available .

 

If you do go through with it, and you can't find parts, i.e. pistons, rings, valve springs, valves, etc. CP will make the pistons, if you send them one, Kibblewhite will do the same for the valve train components. I would caution that it might not be the most economical, but the costs are similar to what you would pay for the OEM bits at current OEM prices, if you could find them. I suggest calling them first.

Here is a link to the OEM pistons, pins, and rings, they are still available, you would just have to bite the bullet on the shipping. The piston pins and stuff can be located in the US at Service Honda. Bearings might be an issue.

https://www.servicehonda.com/oemparts/a/hon/506c84c5f870023420a3ceba/crankshaft

https://www.cmsnl.com/honda-vf500f-interceptor-1985-f_model50160/partslist/0188.html#.XQq1m-tKi1s

 

No, not common anymore unfortunately. VF500 is definitely end of line now. In the last 2-3 years over here bikes and parts rarely come up on Ebay. You get lots of engine parts but no decent engines. I had hoped they might increase in value now they are scarce but that hasn't happened either.

 

I just updated the post, there is more available than you might expect. It can be done, but it's up to you to determine the cost/benefit.

 

Try squirting some oil in the cylinders and see if the compression improves any.

 

Yes, I am sure the readings are off, as I have a really suspect compression gauge. I did a wet compression test and the two rear cylinders went up to 150 PSI then slowly deteriorated back to 60 PSI. It's dead based on this test. But why it is dead is up for debate.

I would love to just buy another engine but they are like hens teeth now and there is no assurance that they are any better than what I have.

 

I found a site in Japan that has standard rings and a gasket set for under $100 USD. For this kind of money why not? Unless anyone has a story as to the quality of the parts...

https://www.ebay.com/itm/84-86-HOND...m2127b1db78:g:4iYAAOSwgkRVTqJF&frcectupt=true

https://www.ebay.com/itm/1983-1985-...298164?hash=item25c1dd5634:g:fdIAAOSwKrxUaaaw

 

Yep did that and it went to about 150PSI.

 

Yes thanks for the encouragement. This is a completely emotional decision. I love beating my head against a wall. Try owning a 1983 Honda Civic like I do!

I really have nothing to lose by at least pulling out the pistons and measuring them as well as the bore. if they are a mile off specification then the motor is scrap. i am not going to attempt to bore this out oversize as I am sure no parts are available.

So..........can you remove the big end rod caps without splitting the cases?????

 

Compression tests are just a very rough guide. An engine will still run even with low compression and give decent performance. If that is the only issue with the bike then I would get the bike into a useable condition and just run it. If it the engine turns out to be toast then at least you have a roadworthy bike and you can fix the engine then or get a better one. It's too easy to get sidetracked into fixing something that might be OK whilst ignoring the more pressing requirements of the rest of the bike.

 

That is what I was hoping someone would say! I actually got it running after cleaning the carbs but it It has a stuck float and flooded with gas. I can rebuild the carbs correctly for cheap and try again. I am guessing it has a blown head gasket on the rear bank but stop leak *could* fix that. Not that I advocate using it but in this case why not????

 

I'd run it.

It will either work or not. Either way you then have more knowledge than you currently have. Get a better pressure tester.