Suzuki DT55 limp mode? Low RPM's

[99yam40]

Re: Suzuki DT55 limp mode? Low RPM's

hard to believe anything would have got through the reeds, I just wonder if something broke off the reeds and someone replaced them but did not get all of it out of crankcase.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Good thought, keep'em coming, need to figure it out before the rebuild. Could we get the same photo of the debris with a dime in it for reference?

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

No sweat, thanks all!

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

I'll go with 99yam40's theory but it's hard to believe someone just left that in there. Do you have a shop to remove the broken bolts?

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

Pistons disconnected from connecting rods. Interesting discovery once I had a real close look at the pistons. I guess I'm not the first to open this crank case since it left Japan. Upper and lower pistons are 0.5mm oversize.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

Yes there is a place about 20 minutes away to pull the broken bolts.

I have to weigh all the pros and cons of this overhaul at this point. I priced everything I will need from Brownspoint.com (haven't compared a lot of online pricing yet) and it's going to be just over $800 including ...

3 carb kits
3 new pistons
3 sets of rings
All gaskets
Water pump kit
Thermostat
Crank shaft oil seals
Fuel pump diaphragm set
Various greases
Replacement of broken bolts and other do-dads

Then I have to pay for the broken bolts to be removed ...

If I do rebuild the engine, what do I have? It's still a bored out 18 year old two stroke. Having said that, what is replacement cost? If I went the re power route, I would likely stick a new (why inherit someone else's problems again?) 60hp Honda 4 stroke on my RHIB. That too has extra costs associated with it, ie remote control replacement for throttle, shifting and steering, gauging etc ... Quick internet search tells me just the engine is $7345.00 ... So safe to assume I would be approaching the $10,000 mark fast. The boat is a 1991 Alliance 420 rigid hull inflatable, that company isn't in business anymore. Not sure it's worth throwing 10k at a 22 year old obsolete boat.

I guess I've made up my own mind here, just had to hash it out. Provided everything is within spec when I get my hands on some inside/outside measuring tools, I guess I'll be rebuilding ... Hopefully when I'm done I'll have my hands on a RELIABLE 18 year old bored out two stroke.

What do you guys think? Is it worth it?

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Makes sense that it has been apart before, for a 18 year old saltwater motor you would have more broken bolts. I'm sure there's still a lot of fun left in that rig, sounds like a good winter project. I have parts from a 91 if you need them.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

Thanks mphelle8vld! We'll I've e-mailed the previous owner in hopes that he can tell me a bit more of the boats history. Maybe he had a past failure that could shed some light on the situation.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

We'll, the previous owner doesn't know of any failures in the boats history. He was 3rd owner. Does anyone know how the connecting rod is removed from the crank shaft? I'd like to get a close look at the big end bearings before reassembly, also would be nice to have better access to the bearing for cleaning/flushing out when I'm at the parts washer.

 

[99yam40]

Re: Suzuki DT55 limp mode? Low RPM's

do not know if that Suzuki motor has rod bolts to take it apart or not, Might check parts break down on what parts are available for your motor
but a lot of the Yamaha 's the crank has to be pressed apart and back together by a shop using a special jig.
The crank assembly with rods attached is sold as a unit.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

I kind of thought as much. Parts are available in the catalogue for the big end bearing and crank pin, but the assembly doesn't lend itself to DIY's like myself ... There are no snap rings like the small end. I have a 20 ton press but no jig to maintain throw alignment during reassembly ... I'm not going to get into that. From what I can tell the bearings look very good, they are smooth and tight . .. That is going to have to do.

 

[stylesabu]

Re: Suzuki DT55 limp mode? Low RPM's

any thought about a reman? I locked up my motor 3 years ago,oil pump quit on me. new power head was about 2000.00 just a thought

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

I think I'll go the rebuild route if the measurements pan out ... I've done some more price digging and I have it down below $700 including piston pins and small end bearings.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

I didn't think the previous owner would admit to selling you a motor with a known issue, how many hours did you have on it before some of that metal jumped into the intake port?

Not sure what repair manual you have, I have the factory manual based on the 94 if you need it.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

I didn't ask him if he sold me a motor with a known issue, I asked him if he was aware of any past issues with the motor or had any information regarding the past rebuild, which he did not. I'm not sure how many hours I had on the motor but I know I put 8 tanks of fuel through it with water skiing and tubing and it ran like a clock ... Until it didn't haha. Here is the manual I have.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Good manual, any machine shop quotes?

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

No shop quotes yet, I'm swamped with other stuff at the moment and will likely have to "back burner" this project for a few weeks. I did however manage to score these ...

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Nice... Looking forward to following your progress

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

So the results are in ... For the cylinders anyway. It would appear that all three cylinders have been bored out. Like the nerd I am I prepared a spreadsheet. I'm getting a few readings that are less than the overbore diameter of 2.8937" ... Tough to be sure exactly what value it was bored out too anyway I guess. I'm right on the wear limit as Suzuki is concerned (no more than 0.004" difference in bore measurement values per cylinder). Hopefully putting a cross-hatching on my cylinder walls doesn't push me too much further out. Obviously the "-0.007's" are negligible as my measuring equipment isn't that accurate. Thoughts?

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Did you ever find a .5 stamped on the number 2 piston? A light hone should be fine but if you're on the fence I believe aftermarkets like wiseco offer up to .040 over.