Hi everyone....

I need help because my bike has been in moth ***** since I was told it has low compression by my mechanic.

A couple of things you should know..Before this low compression issue started I was told by my mechanic that the bike needed a tune up and a cam chain tensioner...

Now, I rode my bike from my home to my GF's home one night (about 1 hour away). About 30 minutes into the ride i noticed my bike was smoking. I got off the freeway and rode into a small repair shop (by chance). I took off the rightside fairing and found a small hole in my loose radiator. The mounting bolt had fallen out and the radiator bumped the mount.. putting a small hole in it.. The radiator was leaking coolant onto my exhaust manifold, therefore causing it to smoke... I used some putty to seal the hole as best as I could and refilled the coolant resevoir. I noticed that there was still coolant in the radiator and resivoir... Just to be sure I took a gallon of water with me for the remaining 30 minutes of riding.

The next day I AAA'd the bike to the mechanic.

He called me and told me that my engine was shot and I needed a rebuild or a replacement... Which seemed odd. He also said that it wouldnt start...

Well, I started the bike that same day... and noticed that it idled very odd and that it did appear to have some sort of compression issue by inspection through the exhaust system.

I thought maybe it was the cam chain tensioner not allowing the intake/ exhaust valves to fully open/ close causing a compression issue...

Then I thought maybe the short block is Ok but that the head gasket may be worn out...

Any ideas? Or am I just totally screwed and in need of a new Long block

 

It would be extremely difficult for anyone to give you help as to whats wrong without seeing the bike. You have a mechanic who has the bike, and he's telling you the engine is shot. Get a better explanation of what he means. if he knows enough about the engine to say that, he should be able to tell you exactly whats wrong, not just that is shot.

head gaskets don't just wear out. They are generally ruined by an overheated engine, which from your description, its possible this happened. if the bike was overheated enough, it can blow out the headgasket, warp the head, or crack the block. Without tearing into the engine, there is no way to know for sure.

How did you tell there was a compression issue by the exhaust?

Is there a reason why you don't trust this mechanic?

Again, the mechanic needs to describe why the engine is shot. it just not starting is not a good enough reason. If did a compression test and its low, it still needs more inspection. Rings, valves, warped head, cracked block or head, can all be reasons why there is low compression. All of which have different results as to what to do. A cracked head or damaged headgasket, would warrant a new head. A cracked block, might as well scrap the engine and but a used complete engine on ebay, then sell the parts that are good off your engine.

Also, if you have any concerns about the mechanics ability, take the bike to another mechanic and have a second diagnosis. I certainly wouldn't take the word of a mechanic who only said the engine was shot without a detailed description of why it was bad.

 

Well I do trust the mechanic, but I think that maybe he didnt do a compression test to the block. I suspect that the head gasket may be shot although the bike didnt over heat. If the block was cracked I think I would know by now, and I have looked at it and dont see and visible cracks (unless the cracks are micro cracks). The head seems like a likely issue... The mechanic told me that the 600 F4i has a special block with Nickle in the combustion chamber... and therefore I have to buy a new block and can have the block bored out and put larger piston rings.. Is this true?

I was thinking about taking the engine out of the bike and taking it to a motorcycle/ watercraft engine shop for a complete inspection... do you think thats needed?

 

JJ - the problem justasquid mentioned is that it appears your mechanic still hasn't told you what the problem is. If he had, you wouldn't have to be making guesses and assumptions.

ANY mechanic that tells you you have a compression problem, and hasn't performed a compression test, needs to be avoided. Unless he can visibly see a reason for it - like a hole/crack in the block/head. A visible gap at the head/headgasket, something like that. Again - he would be able to tell you what he has found. Sounds like you're still in the dark about that.

No - the Cam chain would not cause intake/exhaust valves to not fully open or close - unless the chain is so terribly stretched/elongated that it is allowing the cams to have back and forth play between the teeth and the chain. This is highly unlikely unless your CCT isn't keeping tension on the cam chain. Cam chains just don't stretch out that much - they will likely break first. I believe your motor is an "interference" motor, so if your CCT isn't holding tension and somehow the chain has skipped a tooth somewhere (cam or crank) you'd likely have interference issues in the head, bent valves and the sort.

 

Also - yes the block has a hardened coating on the inside of the combustion chamber - Most aluminum block motors do - either a coating bonded to the cylinder wall, or a sleeve that inserts into the block. If you replace the block, you wouldn't need to bore anything out, you would have a new block with stock cylinder sizes, and your old pistons are stock size - you'd just order the proper new rings and install everything.


He might have meant a hone job on a new block - which is prep for installing new rings, but it is not the same as having a block bored out. Boring a block would also require new oversized pistons.

again - the cylinder walls on these are thick enough to be bored a bit without risking getting the walls too thin. Don't quote me as a resource, but a .010 -.020 over would probably be ok.

Again - if the mechanic is leading you to have to replace the block, and an overbore - he should be able to have a really good reason for it. If not, take the bike or the motor, somewhere else.

 

Thanks for the advice Ad.

I thought that the nickle in the combustion chamber may have been for some sort of lubrication reason or maybe the hardening properties of the metal.. but nickle isnt very hard especially under the high temps of the combustion chamber.
So if i do not buy a new block I can rebuild the one that I have... I have a few questions about that:
1. Can I buy replacement nickle sleeves? Because If I hone the cylinders then I'll be opening them up greater then OEM specs and need to use larger sleeves.
2. Will the new sleeves be thickes and return the ID of the cylinder to OEM diameter or will I need larger piston rings?
3. Is it possible that the only issue is with the head and NOT the block?

Sorry to ask so many questions and for any newbie misinterpretations of the repair process.

 

Ohh one more thing... I may have mis-spoken when I said "bore it out".. I wasnt talking about changing the bore:stroke ratio or the compression of the block.. Your totally correct when you said hone the block. Thats exactly what I was talking about. Thanks for the clearificaton.

 

Whats the compression readings for each cylinder?

 

I havent yet performed a compression test using a guage on each cylinder. I need to though. I think that I may just end up removing the block and taking it for a full diagnosis.
Do you guys have any tips or time saving ideas for removingthe bikes angine. Also, IF I should need to rebuild the engine... would you recommend just buying a used one from a salvage yard? Also, will the 1000CC engine fit my bike? Any common swaps?

 

I think you are jumping the gun way too much here. I wouldn't even be considering pulling the engine until I had a definate diagnosis of whats wrong. Could you imagine going through pulling the engine apart only to find out you had fouled plugs?

I think you need to slow down and properly diagnose the problem.

There are no common swaps for a larger engine. Just replace it with another 600f4i engine.

If the engine is bad, buy a used complete engine on ebay and just swap it. I wouldn't waste my time or money fixing your existing one. If its only the head then maybe, but if there are any internal issues, its not worth the cost of fixing it. This is based on my assumption that you would be paying someone else to fix it. If you can do the work yourslef, it may be cheaper to rebuild. but to have someone else rebuild, its cheaper, faster, and more reliable to just buy a good used one.

but again, do every external test before you even consider removing the engine.

I still think you need to take it to another mechanic and have another diagnosis done to it. But, before you remove the engine from the bike. there is no sense in removing the engine. A removed engine will do the mechanic absolutley no good to diagnose the problem. It needs to be in the bike.