Hi everyone!...

I am new to this site and I need HELP!!....LOL!!

Sorry if this gets windy but I want to be as detailed as possible...

So here goes...

I own a bike shop and usually (read:ALWAYS) work on 4-strokes but one of my customers owns a 2004 Suzuki lta-50 and was complaining about it bogging down at higher r's and wondered if I could fix it for him..so of course being the adventurous type of person that I am I decided to take it on and see if I could get the bike running right for him...I figured..."heck..it's just a 2-stroke so it can't be THAT difficult to trouble shoot and repair"....HAHAHA..was I wrong!!

The plug looked pretty good (better than I expected actually) so I ruled that out as the main problem right away and moved on to carburation (which is usually the root of a LOT of evils with 4-strokers)..I tore it down and cleaned everything good and the jets were all clear...etc...so I tried running it again with the same results...and by the way I also drained the tank...cleaned it out and started with fresh gas so we can rule THAT out as a possible issue...

When I tore the carb down I noticed quite a bit of wear on the slide so I suggested to my customer that we try a NEW carb and he agreed seeings how they aren't that expensive....while I was waiting for the carb to arrive I decided to pop the head and jug off to see how things were doing since the bike is 4 years old and has a LOT of hours on it...well needless to say the piston was showing some pretty good blow-by and there was some slight scoring on both the piston and cylinder walls so I was like "O.K..losing compression and we caught it in time" so he had me go ahead and get a piston and ring set for it also...

Well...I got all the parts the other day...I cleaned all the cylinder ports out...honed the cylinder and put the thing all back together yesterday afternoon and was POSITIVE our problems would be solved and it was going to run like new....well once again I was WRONG!!...she starts right up and idles great but STILL has the upper "R" bogging thing going on...while I was trying different things I discovered what I THOUGHT and what SHOULD be the float bowl drain tube is not actually the drain tube at all...it has VACUUM!!..whats up with that?...just to be sure I sprayed a bit of carb cleaner into that line and killed the engine of course....now..I'm not stupid but this bike has been apart for some time and I can't see ANY place this line should go to...I am completely STUMPED at this point and needless to say with all this time spent trying to trouble shoot after rebuilding the top end I have lost my butt on this job...LOL!!

This all just does not make ANY sense!...can anyone possibly shed some light on this for me??...like...what the heck is that vacuum line doing at the bottom of the float bowl...where does it go (I honestly don't remember it hooked up to ANYTHING when I tore it down) and why is this thing still bogging when you try to give it some rev's?

Any and all advice you may be able to give me would be GREATLY appreciated as this has drug on WAY too long and I need to get it out of my shop....HE is O.K. with things but his wife is starting to get pissy (go figure..LOL!!)...

Thank you in advance and I hope to see some useful feedback soon!

 

First- I am NOT a 2 stroke person !!!; but, hear goes:

Hows the Air Filter? could it be starving for 'air' at upper RPM's???

Most of the 2 Strokes that I know about have 'Reed Valves' - if this has Reed Valves is it possible that they have 'lost their flex' and are 'not sealing' at upper RPM ??? (kind of like 'floating' valves).

Electrical Problem??? High resistance in plug wire, bad ground on coil ???

Sorry, that's all I got. good luck !!!!

 

<div class="FTQUOTE"><begin quote>Originally posted by: NJDale

First- I am NOT a 2 stroke person !!!; but, hear goes:</end quote></div>

Neither am I....as you can tell...LOL!

<div class="FTQUOTE"><begin quote>[i]Hows the Air Filter? could it be starving for 'air' at upper RPM's???</end quote></div>

Air filter is fairly new and clean

<div class="FTQUOTE"><begin quote>[i]Most of the 2 Strokes that I know about have 'Reed Valves' - if this has Reed Valves is it possible that they have 'lost their flex' and are 'not sealing' at upper RPM ??? (kind of like 'floating' valves).</end quote></div>

This one has no reed valves...just a ported cylinder

<div class="FTQUOTE"><begin quote>[i]Electrical Problem??? High resistance in plug wire, bad ground on coil ???</end quote></div>

Seems to have good strong spark and if I am REALLY gentle on the throttle it will slowly pick up the r's...it just bogs if you try to nail it or if it is under any kind of load...

<div class="FTQUOTE"><begin quote>[i]Sorry, that's all I got. good luck !!!!</end quote></div>

No problem...thanks a bunch for the response though...it's the only one I have gotten so far!!

 

i had the same problem but with a lt 80 got the clutch rebuilt & it works fine now

 

Sounds to me like it is 'leaning out' under 'heavy acceleration'. On 4 stoke carb engines there is an 'accelerator pump' on the carb to 'richen up' the mixture when 'manifold vacuum' suddenly drops (WOT). Is there any type of 'enrichment' device that might not be working? Or, is there any type of hose that is suppose to be connected to 'manifold vacuum' that signals the carb to go to 'enrichment' cycle ??

 

Found a web page for rebuilding an LTA-50 carb. I am including the 'link', not because you need to know how to rebuild the carb - but, because it shows pictures before it came off the quad, for hose connections. Hope it helps.

Carb Pictures

 

Found another 'discussion'

LT 50 Restrictor Plate

 

<div class="FTQUOTE"><begin quote>Originally posted by: NJDale

Sounds to me like it is 'leaning out' under 'heavy acceleration'. On 4 stoke carb engines there is an 'accelerator pump' on the carb to 'richen up' the mixture when 'manifold vacuum' suddenly drops (WOT). Is there any type of 'enrichment' device that might not be working? Or, is there any type of hose that is suppose to be connected to 'manifold vacuum' that signals the carb to go to 'enrichment' cycle ??</end quote></div>

Thats kind of what I thought too....but checking the plug it showed very rich..almost to the point of fouling...but I figured out one thing....the choke on these is different...UP is off...just the opposite of what I'm use to on 4-strokes...so needless to say part of the issue was MY bad for not knowing that...LOL!

However...with that resolved I'm still having a hard time getting it tuned properly after the top end rebuild.

 

<div class="FTQUOTE"><begin quote>Originally posted by: NJDale

Found another 'discussion'



LT 50 Restrictor Plate</end quote></div>

Yes...I've seen both of those sites but thanks so much for your efforts in trying to help..I truly appreciate the responses!!

I'm wondering if taking the restrictor out of the intake would necessitate rejetting??...or could one simply set the needle up a notch to compensate?

Also...the carb rebuild write up doesn't show if that vacuum line on the bottom of the carb actually hooks up to anything...my local Suzuki dealer says it's just a vent...but I find it odd that they would have a wide open vacuum...could it be that at one time there was some sort of emissions crapola on that bike that someone eliminated at some point??