2001 GP1200R rear cyl seizure problem. (2nd time)

[EricD]

Just an fyi you replied to post from 2007

[dewzee1200]

Rear Seal LEAK ?

If the coupler cover is not in place the rear seal will leak. This leads to a lean condition, and seizure.

With the cover OFF - what would cause Rear Seal LEAK ?

Just curious TIA

[jeffsntx]

Hydrotoys,

Rear coupler plastic cover in place? WHAT SIGNIFICANCE DOES THIS HAVE TO OVERHEATING/LEAN PROBLEM?

Double post

[jeffsntx]

Hydrotoys,

Rear coupler plastic cover in place? WHAT SIGNIFICANCE DOES THIS HAVE TO OVERHEATING/LEAN PROBLEM?

If the coupler cover is not in place the rear seal will leak. This leads to a lean condition, and seizure.

[bill cosca]

135 hi is to big for these engine the cil will fail again just these time will thake longes on the 135 jet
alcool on the gas will use smaller jets no biger
these is a timing isue the crank may be twisted few deg or the head was damage and have a hot spot and have a pre ignition
and i wont discharge the posibility of a damage crank bering if you pay atention on the picture look like the problem is in one of the ports no the otrers these is very comun on debree coming from the bering closer to these port and same time is so fine is very hard to see
increse the jet is like a patch not a cure

[stockwatch]

Welcome Gera,
I hope we can help you with your problem. You will get bunches of questions and opinions. It would help if you can provide as much detail as possible.

Year/Boat?
Hours on engine since last failure?
When did it happen? What were you doing?
Water in hull?
Rear coupler plastic cover in place? WHAT SIGNIFICANCE DOES THIS HAVE TO OVERHEATING/LEAN PROBLEM?
Aftermarket flame arrestors? Water socks?
Oil Injected or Premix?
Fresh gas? How long in tank?
Have the carbs been inspected or rebuilt?
Has the engine been pressure tested?

Hydrotoys,

Rear coupler plastic cover in place? WHAT SIGNIFICANCE DOES THIS HAVE TO OVERHEATING/LEAN PROBLEM?

[geraban19]

they have lots of alcohol or just sh*t fuel down there (seadoo when thru this in early years)BUT if it were me would check crank index and pressure check seal (soap water test works well) we all know rear cylinder get's hell from twist

later cd

I really thank U guys for all the help due this problem.

[chip]

they have lots of alcohol or just shit fuel down there (seadoo when thru this in early years)BUT if it were me would check crank index and pressure check seal (soap water test works well) we all know rear cylinder get's hell from twist

later cd

[geraban19]

Guys,

I just replaced my bad cyl and increased the main jet from 125 to 135 and set the adjustera like 1 turn, 1 turn and 1 1/2 turn (pto, center, mag) and I had no seizure problems. Pilot jet is #110.

Brazziliam pump gas is too bad guys.

My boat now has a very strong low to mid acceleration and a poor 62-63 mph top speed. Is it really slow for a GP12R stock with out acc pump and a solas prop?


Gera

[Hydrotoys]

No,
everything is fine.

But dont let this single cylinder motorcycle mechanic smooth talk you into doing something that you DONT need, when you have been provided tons of info here, and could have already figured out some important data.

Knowledge is power. Power is speed.

[geraban19]

I better shut up my mouth...

ehehehh

Lets see what we found....

I really want to see a bad fuel pump in the rear carb.


Thanks

Gera

[Hydrotoys]

- Did U noticed that the damaged in the piston is located at the side of the piston not at the front and rear face (intake and exh sides)??

If he is a good mechanic, then when he see's the cylinder and piston together he should KNOW that the damage will always be on the sides with a siezure. The intake and exhaust is not front/back. This is why I avoid motorcycle mechanics.

- Did U noticed that the problem occured on the top of the piston where it is smaller in diameter??? (I know that it is higher temperature area)

No, the problem is those huge freakin deep scratches down the sides and the stuck/broken rings.

- Aren't U thinking that the rear rod (#3 cyl damaged) can be not aligned very well??? Even too much tight or located too back or too front???

The rod aligned very well??? A two stroke mechanic with a knowledge of a pressed crank SAID this?

- There's no wear to the other cylinder and the one that had a seizure had been replated. So, if it dilatate and seizure why it choosed one of the sides to do it more???

Because any two stroke mechanic with knowledge of crank seals, labryth seals, intake/exhaust charge, and engine leaks would know that you can not diagnose a problem like this by guessing about why one cylinder baked itself and the others didnt

- Can be a rear bearing or even a bad rebuild crank be the problem??

Yeah sure, but a rear bearing should have released hard metal pieces into the piston/cylinder and ate up the cylinder head and piston top with ring-shaped divits and missing chuncks. If the rear cylinder has ingested water, you can spin a journal throwing timing off in the rear cylinder, and cause damage. You can also bend a rod this way. Both of these items could easily and quickly be checked, with the crankshaft in the engine, as long as you have the piston and cylinder.

**If your mechanic does not want to pressure test your engine before tear down, then quickly get all your stuff gathered up and run away**

[geraban19]

Guys,

I just talked a couple of minutes with my mechanic by the phone about this problem because we are going to rebuild it tomorrow.

He has been out of all this conversation and has telling me that he was going to make a meticulous analysis.

Today he just told me his opinion and I want to share it with U experient guys. First of all I want to say that he is a 25years of experience motocycle mechanic and I give him a lot of credit.

Here's his diagnostic WHITOUT ANALYSIS the whole engine.... He based it from the repetition of the problem and just looking at the damaged piston. He didn't worked assembling this engine at the prior times because it was treated as an OEM engine that is responsability of other mechanics of the shop.... he takes care of my race skis.

He said:

- Did U noticed that the damaged in the piston is located at the side of the piston not at the front and rear face (intake and exh sides)??

- Did U noticed that the problem occured on the top of the piston where it is smaller in diameter??? (I know that it is higher temperature area)

- Aren't U thinking that the rear rod (#3 cyl damaged) can be not aligned very well??? Even too much tight or located too back or too front???

- There's no wear to the other cylinder and the one that had a seizure had been replated. So, if it dilatate and seizure why it choosed one of the sides to do it more???

- Can be a rear bearing or even a bad rebuild crank be the problem??


What U think guys???? I am really excited to go there tomorrow and find out.

Gera

[Hydrotoys]

Fernando's right about those fuel pumps.
Also he posted this in another post about pressure testing. I thought in your situation, this would be a smart thing to do to.

My recommendation on the single pipe is to bolt up the exhaust manifold in place accordingly and make a round blockoff gasket that goes between the exhaust manifold and the head pipe. There have been numerous report of engines that seized because of water intrusion due to ckack exhaust manifolds,. This is the time to test it.

[geraban19]

Disassemble your carbs and check the entire circuit for debris and inspect all of your o-rings and check valves. I would highly recommend to drill out the built in return fuel restrictor on the body of the carbs and use a 90 main jet on the return line, this way all 3 pumps work together and the pressure is equalized.

U mean open the hole completelly???

I actually running #120 main jet in the return line and after do this I solved my low end problwms.

Gera