84 vf700 with low compression

I have low compression in all four cylinders, been told I have 3 options 1) rebuild it. anyone have a rough price on parts and list. 2)replace the engine.where can I find one. 3) FOR SALE: 1984 vfr700 13168 miles w/low compression $1000.00 ... $500. for the bike $500. for the rebuit carbs.

 

How low is low?

 

#1 84, 130 with tsp of oil. #2 110, #3 95, #4 85. this one keeps fouling plugs

 

You need to do a leakdown test to determine exactly where the bike is leaking.

If it's just a headgasket, the gasket is about $36 and you can do the labor.

You should have about 150 on a cold motor.

 

Don't you have to remove the engine from the frame to remove the heads? I think you have to on the '92.

 

When you say a rebuild, do you mean, New pistons and rings, valves seals plus a regrind.....You need to be more specific of what you think or know that needs rebuilding.

Sounds like to me, that your valves are seating properly.

I've never seen a bike that needed new pistons and rings at 13k on the clock, especially a Honda!

Unless it's been raced really hard by the PO.

ll

 

You only have to remove the engine for the rear head on a VF700F.

 

sell the bike for parts and use the rebuild money on a newer bike.....

 

thanks for all the replies. rebuild it? yes. hopefully rings only, bore out and o/s pistons too if I have to when I get into it. gaskets, valve seals, timing chain and sprockets,etc. the bike is in pretty good shape....other than that.

 

Hey Mason, Nice new Avatar!!!!:hitit:
:focus:

 

More than likely it's something to do with the valves. The valve seats take a beating on motorcycles and require reconditioning after a while. The rings could be losing their seal also, and it could be a combination of several things. From the readings given I'd say that it needs a full rebuild. The cost is tough to say because you could run into a situation where some of the parts are not available anymore. For example, some of the colors of main bearings are discontinued.

With that said - I think it's a good idea to give it a shot. There are VF700/750 engines on eBay quite often, so if you found out that you could not rebuild it you would always have a backup plan. I wouldn't give up on it so quickly.

Where are you located? I've got quite a few VF700/VF750 spares including engines and I might be able to help.

 

thanks Jamie, Im in coventry ct. the cost of shipping and engine may be less than a rebuild. please let me know how much.

 

Engines can be shipped using BAX Global for around $100. They will even deliver to your house, which is handy.

 

Compression readings

I recently did a cold compression test on several bikes including a VF500 and my dead cold VFR 700. I also did a ninja 500 and 250. The ninja,( warm) 500 had one cylinder at 180 psi and the other at 90. I'd say this bike had a valve or head gasket problem. Hard to believe one cylinder would wear out rings while the other still pumps like new. The ninja 250 was only 2 years old but it was used hard daily and the owner never adjusted anything. It had 140/130. The '84 VF 500 had been warmed up and it pumped 155/165/155/160. We called it good but we were looking for 180 X 4, after testing the ninja 500. The VFR 700 had been sitting for months and it pumped 150 X 4. I still wanted 180, but bought it anyway. And finally, the factory manual suggests 190 psi +/- 10%, at least I think thats what I saw. I'll check it after I send this off. I have really enjoyed this discussion of compression/leakdown testing. But, what is desirable compression for a Vf engine?

 

compression

before I get into anything big Ill have to do a leakdown test. the clymer manual says 147 - 213 psi

 

vfr 700 engine

how much for the engine itself

 

I replaced the front head gasket on my 1984 VF750F. It wasn't a lot of fun, but it's doable. The valve timing was the worst part. Oh, and getting the carbs back on wasn't fun either.