RD350LC trouble

[erik_w]

Hello!

I have been offered a 1982 rd350lc dirt cheap and I have a bit of an urge to buy it. But here are some troubles that I would like to know more about before I commit.

the bike refuses to idle, even when warm, adjusting the idle screws does nothing to help. if you pull out the choke however it settles into an uneven high idle and doesn't die down. further the throttle response is very uneven and the bike feels hopelessly weak under 5000 rpm - after that it lives up a bit, but never runs smoothly. spark plugs are a decent color after a spin around the block.

most worrying is however a high pitched squeaking coming from the engine when revving up out on the road - sounds to me like high pressure gas trying to escape a tight opening. I am thinking thus could be the head gaskets - but there is no white smoke from the exhausts.

what do you think? is it a simple carb clean or is it a total top end rebuild? new reed valves?

the bike looks nice so it is interesting - but I don't want to buy a total project this early in the summer.

best,
Erik

[PeteS]

Crankcase seals probably need replacing. Pretty common on two strokes. This is air cooled, no? They are pretty easy to work on.

Pete

[oldbike54]

Crankcase seals probably need replacing. Pretty common on two strokes. This is air cooled, no? They are pretty easy to work on.

Pete

 LC = liquid cooled . Does sound like crankcase seals , not too difficult if they are available .

  Dusty

[Mike Harper]

The first thing to do is clean the carbs.  The Primary (idle) jets or passageways are plugged

Dead giveaway is the use of the choke ( enrichener )  That bypasses the primary jets

Squeeking is most likely the head gaskets, what does white smoke have to do with any of it?

[oldbike54]

The first thing to do is clean the carbs.  The Primary (idle) jets or passageways are plugged

Dead giveaway is the use of the choke ( enrichener )  That bypasses the primary jets

Squeeking is most likely the head gaskets, what does white smoke have to do with any of it?

 Mike , he may be referring to steam . LC model .

  Dusty

[Mike Harper]

OH,  I forgot it was water pumper

[erik_w]

yes, I thought it would smoke white when burning the coolant - but it doesn't ...

I really don't want to be the seals - then it's an engine out job. what's a dead give away for the seals being bad?

[Steph]

Back in the '80s I had a RD350 YPVS ( a later RD350LC with Power Valves) and  remember the choke lever position being poor/defective. When I closed it had to pull it back 1mm or so for it to run right.

It was a fun bike 

Mine looked like this

[oldbike54]

yes, I thought it would smoke white when burning the coolant - but it doesn't ...

I really don't want to be the seals - then it's an engine out job. what's a dead give away for the seals being bad?

 Triple Jim probably has a better answer , but here is mine . Pressurize one cylinder , or both if possible . If it leaks through the exhaust it is either CC seals or rings .

  Dusty

 Edit , I should have mentioned that the piston needs to be at TDC on the side being tested . OOPS 

[Steph]

Thread now with Guzzi content 

[Two Checks]

I would guess crank seals leaking making the mixture lean. Applying choke enrichens it.
Neat and somewhat rare bike these days. If the price is right, I'd buy it.

[Triple Jim]

Normally, to test the seals, you plug a cylinder's intake and exhaust ports and pressurize a cylinder to about 6 psi, then watch to see how fast it bleeds down.  Then you repeat with vacuum.  Since you plug the intake, the rings don't enter into it, and you measure only crank seal leakage. 

I believe all the RDs used aluminum labyrinth seals between the two cylinders, which can't go bad unless the crank bearings get so worn out that the seal parts contact each other.  Since lab seals don't seal perfectly, you have to plug both exhaust ports and both intake ports, and test both cylinders at the same time.

The good news is that only the outer seals are rubber, and can be changed without rebuilding the crank.  On a Kaw triple, you can change the outer seals without splitting the crankcase.  I'd guess you can on an RD as well, but I'm not positive.

Here's a forum with a lot of RD activity, and a lot of very experienced RD guys available to help:
http://www.2strokeworld.com/forum/index.php

If you don't mind working on it to get it into good shape, a cheap LC would be a great 2-stroke to have.

[LongRanger]

It's a very simple engine and a fairly desirable and collectible bike. For spares, your friend is HVC Cycle in Lincoln, NE. They did wonders for my '73 RD350. They carry everything you'll need to get this bike running properly, including NOS parts.

[Waltr]

  YOU SHOULD PROBABLY JUST FORGET ABOUT AND LET ME BUY IT!

[Sasquatch Jim]

  Whatever leaks out the crankcase seals does not burn in the cylinders, hence the uneven running and lack of power.

[Cam Lay]

Middle Child talked the neighbor out of the air-cooled 125 version, literally a barn find (they brought it home strapped to the bucket of the tractor). Same symptoms - we had to clean the carburetors probably 5-6 times before it ran.

He rode it to school a couple of times, and could hardly get through the parking lot for all the guys my age wanting to tell him what a cool bike he had. :-)

Buy it!

[jabberwocky]

  Whatever leaks out the crankcase seals does not burn in the cylinders, hence the uneven running and lack of power.

That's not generally the problem with bad crank seals. The real problem is that the engine will pull air in through the leaking seal, creating a lean mixture which will hole a piston.

[cwiseman]

The poor idle def sounds like plugged idle jets, really doubt the crank seals are bad and that is a easy fix if needed. The squeaking noise is odd but probably not a big deal. Possibly chambers rubbing together near the head. I've seen that happen, simply readjust for more clearance. Maybe water pump seal is dry causing the squeak??
Look like yoy got a great bike, the LC is rare and pretty damned cool! Have fun and enjoy!
Another great person to get parts from that will give you one on one personal attention is John Rodenhiser at economy cycle, One of the best to deal with!

[erik_w]

The poor idle def sounds like plugged idle jets, really doubt the crank seals are bad and that is a easy fix if needed. The squeaking noise is odd but probably not a big deal. Possibly chambers rubbing together near the head. I've seen that happen, simply readjust for more clearance. Maybe water pump seal is dry causing the squeak??
Look like yoy got a great bike, the LC is rare and pretty damned cool! Have fun and enjoy!
Another great person to get parts from that will give you one on one personal attention is John Rodenhiser at economy cycle, One of the best to deal with!

what chambers are those?

when you say that changing cc seals is easy - does that mean I can do it without pulling the engine out?

[Vasco DG]

what chambers are those?

when you say that changing cc seals is easy - does that mean I can do it without pulling the engine out?

Oh boy. 

More fun than underpants full of piranhas but probably not what most people would see as 'Easy' nowadays.

Pete

[oldbike54]

 Chambers = exhaust . Memory tells me it is necessary to pull the engine to replace the outboard seals . Once again , TJ suggested a peek at the too smoker forum , most of us here haven't owned a Scott or a Bantam in years 

  Dusty

[rbond]

Clean carbs for sure. Lack of power and weird noise is probably the exhaust power valves sticking or just stuck in wrong position. Get it thought it will be worth it in the long run.

[Steph]

After the air cooled RD350 and RD400 came the RD350LC (non-powervalved) then the power valve version called RZ350 in some markets and RD350  YPVS in others.

The OP's '81 -'82 model:

[Steph]

My friend in Ottawa still has a rough looking RZ500 in his shed.
There are worth quite a bit in good shape, I'm sure I'd take an offer if someone was interested.
I believe the RZ500  were sold in Canada and not officially in the States, so pretty rare.
I'd be a nice project...

Ref that original post:
http://wildguzzi.com/forum/index.php?topic=63398.0

[cwiseman]

Winner winner chicken dinner! The 350LC wasn't available here in the USA, most that got here came through Canada.
As Pete mentioned not a easy task basically the crank seals are hidden behind the ignition on the left side and the clutch/water pump on the right. It may be able to be performed in the bike but probably easier to yank the motor out and throw her up on a bench.

Id definitely strongly suggest a proper cleaning of the carbs, use a propane torch to burn the crap out of the idle jets while holding them with a pair of needle nose pliers. You'll usually see a puff of smoke once the crap gets hot enough to ignite and burn away.
Change the coolant and see how the old gal performs before going crazy doing a bunch of work that may not need to be done.

Once you understand how a 2-stroke works they are pretty damned simple. Air goes through carbs and mixes with gas while a shot of oil get in the mix one way or another, then it next goes into the bottom end of the engine where it lubes the bottom end bearings, next it travels up passages on the side of the cylinders where the ports direct it into the cylinder, piston comes up closing the ports and the final squeeze before she gets ignited. When the piston travels down it pushes the next charge out of the bottom end back in the cylinders! Now the chambers use a sound wave to push part of the un burnt fuel back into the cylinder and keep it there till the piston seals it off before getting ignited!
Quite simple or vastly confusing?

[Steph]

Winner winner chicken dinner! The 350LC wasn't available here in the USA, most that got here came through Canada.
As Pete mentioned not a easy task basically the crank seals are hidden behind the ignition on the left side and the clutch/water pump on the right. It may be able to be performed in the bike but probably easier to yank the motor out and throw her up on a bench.

Id definitely strongly suggest a proper cleaning of the carbs, use a propane torch to burn the crap out of the idle jets while holding them with a pair of needle nose pliers. You'll usually see a puff of smoke once the crap gets hot enough to ignite and burn away.
Change the coolant and see how the old gal performs before going crazy doing a bunch of work that may not need to be done.

Once you understand how a 2-stroke works they are pretty damned simple. Air goes through carbs and mixes with gas while a shot of oil get in the mix one way or another, then it next goes into the bottom end of the engine where it lubes the bottom end bearings, next it travels up passages on the side of the cylinders where the ports direct it into the cylinder, piston comes up closing the ports and the final squeeze before she gets ignited. When the piston travels down it pushes the next charge out of the bottom end back in the cylinders! Now the chambers use a sound wave to push part of the u burnt fuel I. The exhaust pipe back into the cylinder and keep it there till the piston seals it off before getting ignited!
Quite simple or vastly confusing?

I believe the USA briefly got the later power valve model. I don't think it was a big seller. The '80s were all about 1/4 miles figures on "factory prepped" stock bikes for journalists...

Here's Kenny on one:

[cwiseman]

Yes we did indeed get those called the RZ350 over here, I want a yellow and black Kenny Roberts edition badly!!!!! My first street bike in the early 90's was a 1975 RD350 and I still have her, wonderful little bike with great handling.

[LowRyter]

http://www.cycletrader.com/YAMAHA-RZ350-Motorcycles----CycleTrader.com/search-results?make=YAMAHA%7C2321194&model=RZ350%7C764863078&vrsn=hybrid

wow.  pricey little buggers now.  I was guessing a nice one was maybe $4k. 

[Triple Jim]

The 10k one is a bit of a stretch.