1990 Suzuki DR250 - My first evar motorcycle

In reply to paranoid_android (Forum Enabler) :

That "hanging" behavior is typical of slide issues and small air leaks- I'd be looking very hard for anything that might let air get around the throttle plate or the idle adjustment screw or something wrong with the pilot jet.  You can also ride around it to some degree by leaving the bike in gear longer as the rpms drop, but the root cause is in the carb somewhere.

As far as what rpm to ride at, it's personal preference but I prefer to be somewhere in the midrange when the trail gets difficult because then you can either slow down or speed up a bit without having to worry about shifting immediately.

@Jesse Ransom- that is exactly what I said, that's funny!  In fact I said it at least three more times during the ride, but that footage didn't make it into the video.

@Professor Brap- hey, thank you for that information!  Honestly I don't know if my 90 has a rev limiter on it.

In reply to paranoid_android (Forum Enabler) :

It should, like 99% sure. 

Does it have a CV carb or a flatslide?

On my '90 DR350s, if I killed it, it was like 20 minutes before it would start again. The best mod I did was a White bros Mikuni carb which got ride of the CV.

In reply to GPz11 (Forum Supporter) :

They have CV carbs, only the "S" dirt only models got pumpers. 

I also had a '90 DR350SE as my first real motorcycle, it was a very tough old beast but an absolute bear to restart if you flooded it.

both the 250 and 350 are really bad about timing chain strech, are you sure it didnt jump a tooth? You probably would have noticed when you had the head apart but mine got some RTV stuck in an oil passage and it wiped out the pads on the rocker arms. 

This is an S model, so it has the TM33 pumper carb with a flat slide.  I've had it apart for multiple cleanings and replaced several parts, including the slide.

The seller told me when I bought it it had carb issues, but no other details.  It was cobbled together pretty poorly, including silicone caulk instead of the float bowl o-ring.

There were no signs of the timing chain having skipped when I had it apart.

When the bike ends up on its side, it is a complete pita to get started again.  I figured due to flooding.

OK, after a fall, did you try to clear it out?

Hold the throttle wide open, pull the compression release, and then just start kicking for a bit.

Then close the throttle and try starting it like normal.

The CV was a real PITA but once I went to the flat slide, it was night and day difference.

In reply to GPz11 (Forum Supporter) :

I did try clearing it out after dumping it, being a new rider it happens fairly often 

But I was holding the decomp lever open and throttle closed, then kicking it over 10-12 times.  I'll try it with the throttle open nex time, maybe that's the ticket.  Thank you for that tip!

In the mean time I'll go back to looking for air leaks in the intake and carb.

In reply to paranoid_android (Forum Enabler) :

The boot from carb to intake port is a known spot to check for leaks. Also is air cleaner clean?

Got my last ride of the season in yesterday, this time at Long Lake trail near Cadillac.  Video and more words to come...

In reply to paranoid_android (Forum Enabler) :

Looks like you live in a really beautiful area for riding (or can get there from home). I mean, I do, too, in the PNW... But something about those deciduous woods is just gorgeous. It really makes me want to try out this dirt bike thing.

In reply to Jesse Ransom (FFS) :

The closest trail to me is a five hour drive round trip.  This particular trail is six hours round trip.  Doing it all in one day is tiring, but well worth it!

Ok, here we go!

First the trail map:

The trails I've been on to this point were 50" wide, so ORV's can go on them too.  This trail is a 24" wide motorcycle only trail, with plenty of whoops and roots.  For my riding ability this meant a slow and steady pace.  I covered 10.8 miles of the trail in about 3 hours 11 minutes.  But more importantly- I didn't hit any trees 

Video is here, it's long.  Naturally I cut out all the parts where I fell over, got stuck, thought I killed the bike by catching a tree stump with my foot peg, etc.

I felt good enough to keep going, but rain and snow made visibility a challenge.  And I was wet.  So I took a DNR road back to the trail head and called it a day.

This was the first ride on a new rear tire too- a Kenda K760 Trakmaster:

I think it was probably good!  Honestly the wet leaf layer on the trail made it hard to judge it's traction, because there was very little traction to be had.  But I think it will be a winner for my kind of riding.

The bike ran like it usually does.  The idle would tend to drift up for a period of time, then it would drift down- to the point it sounded like it wanted to stall.  Before this outing I checked for vacuum leaks again and didn't find any.  But with no more trips planned until spring (that I know of), I'll be able double check the work I've done to this point.  My thoughts are pointing to the cam timing chain and tensioner, and another thorough go-through on the carb.

I looked a map and I'm 99% certain I rode that single track 27ish years ago. It was fun then and probably why I'm dragging my kid to the woods now, dirt bikes are still fun. 

Still chasing the root cause of the annoying hanging idle.  Since metty (above) asked about the timing chain condition and I couldn't accurately answer, I took it apart to inspect it.  The timing was in fact correct, so it hadn't skipped a tooth.

The manual says to replace the cam timing chain when the 21 link distance gets to 5.070".  My chain appears to have .070" to go before it reaches that point.

The links all move/flex freely.  I don't suspect it needs to be replaced at this point.

The cam timing sprockets don't look that bad to me either.

So I don't think this is it.  The timing chain auto-adjuster seems to be working correctly too.  When I removed it it was extended to half its available travel, and the mechanism is moving freely as it should.  The plastic tensioner and chain guide both look good too.

Back to the carburetor.  One underlying suspicion I've had is there was too much play between the slide and the carb body.  Earlier this year a new slide was installed, but there was still some play.  A couple weeks ago I made a shim thing out of brass shim stock that fits on the slide to negate the slop even more.  That didn't make a difference either.

Removed the air box and intake boot for thorough cleaning and inspection.  They still look good.

After I get the engine back together I'll remove the carb again to go under the microscope.  Again.  

Is the vaccum port on side of carb hooked up or plugged? 

In reply to Professor_Brap (Forum Supporter) :

No vacuum stuff on this model.  This carb has a flat slide and an accelerator pump.

Advice and information requested from those more knowledgeable than me.

I don't have the clutch side of the engine back together because I can't find a replacement kick start idle gear.  Actually this search has been going on for two weeks with no answer.

This is my gear, approaching a summer teeth condition:

Suzuki parts drawing here for reference, it's part #30:

New and used part searches indicate the part is unobtanium.  It's listed on several sites with 0 availability.  This is true of the DR250 and DR350 models.

Honestly I think I can live with the boogered teeth, what set off an alarm is the bronze bushing pressed in the gear.  The radial play when the gear is on the shaft is excessive.  Actually it's downright floppy.  Neither can I find a replacement bushing.

So what would you do with it?  Hold out for a possibly ok used one on eBay?  Put it back in and run it till it fails? Currently I'm considering sourcing a bronze bushing from McMaster Carr that's close in size and devising a way to fudge it in there.  I did just post on ADVRider to see if there is a close enough one from another make/model to get by, no info yet.

In reply to paranoid_android (Forum Forumer) :

If you think a replacement bushing will do the job, I'd go that route.  If you want the whole gear, Revzilla seems to think they have it going by the part number but who knows, could just be their inventory system.  I'll keep poking around for new ones.

EDIT: This should take you to the three stores google thinks have it.

Hello paranoid_android,

Did you ever get your hanging idle sorted out? I am also the proud owner of a 1990 DR250 dirt model (as of last year) and seem to have the same issue. Everything else seems to run fantastic, but as soon as you touch the throttle it doesn't seem to want to settle back down unless I have it in gear and let out the clutch to get the RPMs down first. I'm also in Michigan and am itching to get out and ride, but I would really like to get this figured out first. Any insight is greatly appreciated.

The idle issue was never resolved, but the DR250 is now in my care. I plan to put a new carb on (TM33) to hopefully solve it. 

In reply to EvanB :

I still have some Dr parts hanging around if you want them. 

In reply to EvanB :

I'm curious how the TM33 swap goes. I've heard getting the jetting right is tricky. If you do get a TM33 to play nice please let me know and I'll probably do the same!

Thanks.