Both engines wont stay running Help

[MichiganMan]

I just picked up a 97 speedster that has been neglected. When I got it the engine bay had water up to the air box. I drained the exhaust, drained the fuel tank, pulled the plugs and cycled the pistons to pump out the water oil mix, pulled the carbs and tore them down and cleaned them out.

Now I can get both running but I cant get either to stay running without using starting fluid or choke it completely. Any help would be greatly appreciated

 

[Dr Honda]

1) Did you check the compression?


2) if the engine was submerged and the crank was below the water... then the end of the shafts would have rusted, and then ripped the seals up. That will cause it to run lean.

3) When you rebuilt the carbs... did you check the pop-off?

4) DO NOT keep running it on starter fluid. There isn't any oil in it.

 

[MichiganMan]

1. going to test it this weekend

2. if you could explain that would help

3. what is the pop off

4. i realized that so i stopped trying thus asking for help

I have built a few offroad truck motors but this is a new thing for me.

so step one check compression? shoule be around what 130-150?

 

[MichiganMan]

Dr. H

Ok so I did the compression test
-Port Engine
- Bow 90lb/sq.in
- Stern 145lb/sq.in
-Starboard Engine
- Bow 145lb/sq.in
- Stern 145lb/sq.in

When I had the plugs in and carb off there was a light brown liquid pumping out of the pulse line. I'm assuming this is what my lower end is full of? How do i drain it and would this require me to drain the oil in the lines also?

 

[Dr Honda]

Well... that answers the question. Your port engien is not happy. 150 psi is spec on a fresh engine. anything above 135 is OK. 90 is done.


To answer your other Q's:

1) got it above

2) Since it's a 2-stroke... the air/fuel goes into the lower half to lube the bearings. IF... you damage the crankshaft seals (with a rusted shaft) then you will get an air leak, and run lean. (and can cause a melt down)

3) Pop-off is the equivalent of setting the float bowl level on a conventional carb. Since the regulator in the Mikuni carbs allows fuel to flow... we test where the needle and seat open by pressurizing the carb, and finding what pressure you can push the needle off the seat.

4) Good.

 

[MichiganMan]

ok so pull the port engine,it needs to be torn down right? and what am i looking for when i dive in. next get gauge to test the float or pop-off on both carbs, im assuming since i have them all torn down i should just rebuild them now? Now should i pull both engines to prevent having to come back to do the starboard side next month? sorry for being such a noob, thanks for the help

 

[Dr Honda]

If that's the factory (15 year old) engine... then there really isn't anything to look for. It needs a complete rebuild.

If you go to Mikuni's web site... you can download the SBN manual. It shows proper testing methods... and full explanation of the carb internals.

As far as rebuilding the second engine... it's going to give up eventually... but it may last a season or two more. So... personally... I wouldn't pull it until it needs to be rebuilt.

 

[MichiganMan]

Motor is out as of 10 minutes ago. Ive seen a few different threads on rebuilds any you would recommend? what kit would i be looking for and what do they run?

 

[MichiganMan]

so here she is torn down. it was full of MOW (mud-oil-water). the piston rings were seized to the piston, so im assuming that is what was giving me a compression issue. other than the carbon build up on the tops of the pistons i dont see any scoring or groves on the pistons or sleeves. just a normal rebuild kit should be fine right? anything else i should do while i have it torn down?

 

[El Toro 33809]

Interesting situation you are in..... How much are you willing to spend? With the particulars you mention, it could use a crank and at least one piston assembly and gaskets. Nyou are looking at least $450 for that option. A remanufactured engine can run less than $800. Doing that, you would have one motor that was completely fresh. Or maybe you could find a good used engine for it.

 

[MichiganMan]

so a top end rebuild wouldnt take care of it huh?. they run around 200-250 from what ive seen. whats the issue with the crank?

 

[El Toro 33809]

With the "MOW" you found in the engine, I personally would be concerned with rust and corrosion on the bearings. The may last a couple years, then again, maybe only a few hours. Let's see what Dr. Honda thinks.