gsx 800 rfi motor lost compression again

[wolfie]

I bought my 2000 gsx 800 last year and ran it about 10 hrs. with no problem except once in a great while it would stall for no reason but start right back up. (no big deal) I sold the ski to a friend this year and after one run it slowly stopped running. Took a compression test and found stator side had 35 lbs and pto side had 165. Took head off and there was a chip in the piston on the top which was giving me loss of compression. The rave valve spring was missing so I thought the rave valve might have caught the ring and broke the piston. Bought a wsm kit and let full bore bore and match pistons and jugs and cut rave valves to fit. Reassembled motor and spent 2 hrs breaking top end in with no problems. motor ran great. Gave back to my friend and ran it for about an hour and it slowly lost power again. Took it back to the garage and 35 lbs in stator side again and 165 on pto side. Took head off and this time piston had bad pitting and missing piece on same side again and the other piston was starting to do the same thing. I don't no where to start looking for the problem. looks like it might be a lean condition from bad injectors or low fuel pressure. if the hoses that go to the head get swapped around could I over heat it? confused can anyone give me a direction to go in. can set up some pictures if needed. thanks in advance.

 

[purple_people_eater]

i'd start with having the injectors cleaned. is the rod bent on that side? are the crank seals good on that side?

 

[wolfie]

going to rule out bent rod for 2 reasons it is now happening on both sides and checked crank and rod before reassembly and was ok. do you no of a cleaning service for the injectors or am I better off buying new?

 

[purple_people_eater]

http://www.fuelinjectorman.com/

i used this guy, very fast turn around and knows his stuff. cost me about 50 bucks for the last rfi injectors i send him.

 

[wolfie]

is the rfi considered a top or side injector I would think side

 

[purple_people_eater]

Fuel comes in from the top, so it's a top feed.

 

[wolfie]

finally had a chance to upload pics does anyone have an idea of what had happened here 3hrs on top end rebuild ???

 

[wolfie]

other side

 

[Mekanix]

Seems super lean.
Also what about the head now. Must be pitted, Any high spots are going to contribute to detonation.

 

[wolfie]

I think lean too am going to have the injectors looked at. is there anything else than can cause a lean condition on an rfi system ?

 

[LouDoo]

While you have the engine at least partially dissembled I think I would also check the squish area, it may need a thicker base gasket, 165psi is about 10psi too high which could be causing per-detonation, causing a lean condition.

Lou

 

[AdamXP800]

Id be worried about the little bits of piston being in the bottom end. Are you planning on just a top end rebuild again?

 

[wolfie]

loudoo when I put engine together it was recommended to me by full bore to use a #6 jug gasket so this wouldnt happen. sent injectors out today to get looked at and cleaned. still think it was injectors will find out

 

[wolfie]

Adam , I took apart everything last time and it was pretty clean for 250 + hrs think I should do it again ??

 

[- BiRkS_]

At 250 hours on a stock crank on its 3rd top end? geez thats pushing it.

I would at very minimum split the bottom end and inspect all the bearings, especially the CB bearings and replace the crank seals. IMO there is no point trying to re-do something a third time and all it will cost is some gasket maker and seals. And the peace of mind that everything is OK.

As said earlier you will have to sand down the pitting on the head and you MUST follow a proper break in. 2 hours is nothing. heck after 10 hours I still avoid prolonged 3/4-wot exposure. and thats even more crucial on a fuel injected ski because you don't have the extra mixed gas the first tank. After every run on a new engine always check the plugs. you can catch a lean condition well before it causes damage like that again. Call me anal, but I've yet to had a rebuild "blow up" other a leaking base gasket once that i had to re-do, but no mechanical failures. Engine work cannot be rushed that's when things go wrong.

 

[wolfie]

this is about my 10th rebuild and my second fuel injection motor. looks like my mistake was not assembly but the dam fuel injectors were bad. will never rebuild without new or rebuilt injectors again. will take apart again to have piece of mind. full bore told me 2 hrs on a top end rebuild before full throttle is more than enough and 10 hrs on a complete rebuild.

 

[wolfie]

ok, have put new motor in and have had injectors cleaned and was told they are 100 percent good. installed engine and within 45 minutes the pto side leaned out again. what else could be causing a lean condition in this rfi engine. oiler is working good because all bearings in the crankshaft were well lubricated. other side of motor looks perfect. timing is correct set by engine builder. gas is fresh. would anyone like to put their 2 cents in. ( low fuel pump pressure but gets full throttle??)

 

[griz400]

your first post, you state -- Took a compression test and found stator side had 35 lbs and pto side had 165.
now you lost your pto side ... if the top of your piston is looking like that, pull the piston and see if the bottom, under the skirt is oily, if so your injector is dumping fuel and washing cylinder, and seizing engine, i lost 2 motors the same way, i replaced both injectors and also put an oil pump on for shits and giggles .. from nick at westcoast for a good used oil pump. fiveomotorsports for injectors

 

[wolfie]

I had the motor rebuilt by tom at ses who is working with me on this problem. when I was running the motor under load at first it was ok then it stalled and would idle at around 1200. when I ran it one more time it would get up go and then stop. it would take a few times of cranking the motor and then it would ran again and then shut down. felt like it was starving for fuel. took it home and did a compression test and flywheel side was 160 and pto side was 110. Took exhaust manifold off to look at pistons and flywheel side still looked new and pto side was dry and the center of the piston look like it had a half inch circle in the middle. (detination ) was happening. the dryness was from all the aluminum getting hot. could not take head off because it would void my warranty. motor will be back on Friday with a hone to clean up the cylinder and a new piston and rings. Tom said the oil pump is working because when the crank was looked at the bearings were well oiled. Said the entire piston was dry and had no real explanation of what might have happened. I sent the injectors out to fuelinjectorman and said they were good to go. I need to do more before I put the new motor back in. fuel filters - fuel pump - fuel pressure regulator and if it happens again I am thinking the computer might be bad? any othe suggestions ( started to get frustrated but to clean off a machine to give up to much fun to ride )

 

[griz400]

if you dont want to believe me about replacing your injectors cause of "piston wash" then thats ok, little reminder -- they are 14 years old ...

 

[wolfie]

didnt say I wasn't going to change them but there is no sign of the pistons being wet on the bottom and I just paid $50.00 to have them gone over by someone who does this for a living. just a little hard to believe after what I did. I am changing the fuel injectors,fuel rail, fuel pump, regulater,and all filters this weekend.

 

[griz400]

well, i was just trying to "edit" post number 18 and explain it all what i/m talking about, but, now I am not allowed to edit my posts i guess anymore....
so, this will be my last post on this forum .... seems strange ....

 

[racerxxx]

well, i was just trying to "edit" post number 18 and explain it all what i/m talking about, but, now I am not allowed to edit my posts i guess anymore....
so, this will be my last post on this forum .... seems strange ....

Nope, NO ONE can edit a post past 2 days. When a user on here smoked his entire build thread a few months back the rules changed. It's nothing you did. Just PM [MENTION=2]hfgreg[/MENTION] and see if he can do a little magic to let you edit. No need to get upset....yet.

 

[hfgreg]

well, i was just trying to "edit" post number 18 and explain it all what i/m talking about, but, now I am not allowed to edit my posts i guess anymore....
so, this will be my last post on this forum .... seems strange ....

We had to do this as a member decided to go through an ruin perfectly fine year old threads by deleting all of their content. Let me know what post you want updated and I can help.

 

[wolfie]

sure hope this forum can get griz400 back. he was only trying to help with a problem he seems to have been threw before. This one is not cut and dry. even the engine builder is having a problem putting a finger on exactly could be causing the problem.(nothing but good things to say about tom at ses he is trying hard) I have been a marine mechanic for 22 years and hate throwing parts at problems to fix them but we are starting to do it with this detination problem. will continue to update until problem is solved. I have been reading the rfi thread and it has a lot of good ideas.