If you don't laugh... you are not well.

Well this is not an XJ thing, not even Yamaha...

But does cover Mikunis... and I hope you guys get a kick out of it.

We recently picked up two Ski-doo sleds... a 91 Formula Plus (521cc 2 stroke, cylinder, dual mikuni slide carbs) and an 86 Safari 377 which runs first pull.

$100 for the pair. Yep. Sweet deal.

Anyway, broke the pull rope on the formula (of course, MY sled...)
Trying to diagnose the motor problems. POPS once, then won't even pop for an hour later. But never runs.

We pull the exhaust off to get to the pull start, replace the rope but still have the exhaust off. Pull the airbox to get the carbs out to see what's up. Not even connected to carbs, well I bet THEY'LL be pretty!

Clean carbs. Which BTW were terrible, rush, chunks of solids in the 'drain' at the base that lets you get to the main jet... main jets plugged solid. Pilots solid as well.

Salvaged only two rubbers in whole carb (bowl gasket and drain/jet access)

So carbs are on bench, airbox off, exhaust off, fuel lines all obviously disconnected, even the prime tubes not in place.

Basically, two cylinders with wide open intake manifolds and a Y pipe manifold for exhaust.

Just the basic motor right?

I had just pulled the motor 5~6 times myself, to test the new 'shorter' rope that I hoped would work. Decent.

Geoff cleans the plugs, and drops them back in.

"Umma give it one more test pull then we'll go get the carbs and put em in"

PULL.

Pop Pop RARRRRRRR ARARARARAR ARARRRRRR

WHAT THE?!!??!

It revved out of control, TORE the dirt out from under it, FLUNG my 3 foot long exhaust expansion chamber, and bolted towards the shed.

NO CARBS. NO EXHAUST. On a TWO STROKE.

It nearly took out the shed, but stalled out 6 inches away.

Geoffs first instinct: go for the key. Before he got a hand on it - it was hauling !$% away from him.

My instinct?
I flippin booked it. So loud, SO SO loud, I thought it was gonna blow. I RAN like a 300 pound baby. HAHA.

Anyway, hope you guys enjoy the story.

On a more serious note -any ideas WHY I only get ONE pop out of it, and it will not fire up? I got the cleaned carbs back in, and it does the same it did with the terrible dirty carbs. One pop, nothing else till it sits a bit.

Thinking it might just need a good blast of starter fluid and hope it stays running long enough to clean out any junk?

First time with Mikunis, and they are the slide style (no butterfly, no choke, no enrichment, just SIMPLE!)

Hope you enjoyed the story, was hella funny for us! Aside from Geoff trembling a bit afterwards... hahaha...

 

91 you hsould have a primer pump on the dash correct? DOn't pump it more than twice after you feel fuel in it. If you did hehe... welcome to the built in semi-auto flood mechanism. They flood soooo easy and if you flod it better just go back inside for 30min and try later they are a bastard!!! THat said when you get the primer down it will start first pull everytime and I actually like the primer way better than the choke sys. by removing the carbs and pipe you let the engine have the air it needed and since it is a rotary valve motor and had fuel in the bottom end you had everything needed for ignition. You also could have float valves that are sticking and letting gas leak into the bottom end and therefor flooding the motor. TO set them up there are only two screws on in the side of the carb that is centered to the slide this is your idle screw one on each carb body. you want it to idle around 12-1400rpms. there is also an air screw start at 1 turn out. when you ge the sled running and idling prop the back up so the track isn't on the ground slowly turn the screw out until you reach the highest rpm then back off 1/8 a turn. then do the other side the same. then adjust idle. you could still have some plugged passages if it run on either you know it's a fuel problem. You might want to do a compression test as well as with the carbs and Exh. off you improved the flow a bit anything under 120 is getting pretty low for the two stroke. but it'l still run. make sure the airbox is clear of obstruction as well.

 

Holy run-on sentence batman! haha

Soooo that screw which I didn't touch for the reason of not knowing what it was - AIR screw?

The idle screw I left alone, assuming they were both set right. lol. No need to fool with something if it's right - and I won't know how to tell till the motor is running.

So I should set my air screw @ 1 turn out. Try to get it running.
If I get it running, the idle screw is what I want to get idle right. Then adjust air screw till get highest RPM, then back off 1/8 turn?
Then adjust idle again?

Kinda worried bout the whole DUAL idle screws (two carbs) and yet... two cylinders... like, 1 idle on the XJ's. How do you adjust an idle on ONE cylinder, that is affixed to another, without touching THAT idle? Odd.

Time to learn bout two strokes, more than what I just know from basic knowledge.

I don't know what size plug threads they are, but my comp tester is 14mm and 18mm, I think they are 14.

Thanks for the tips!

Hope you laughed. haha.

 

I wish someone had of recorded and put on youtube

 

HAHAHAHAAAAAA =)

 

I have never claimed to be well -LMAO - good story thanks for sharing.

Would have made a great Youtube though

 

Even if I set it up to do it again... it could NOT be as funny... haha

 

It's amazing how long the damned things would run on vapors, eh? I test-fired my 650's motor on chemtool... got about 200 revolutions on just a light mist of all 4 intake ports

 

Well with a two stroke there's plenty of vapors in the crankcase, it just needed spark.

Was CRAZY loud though, without the entire exhaust. And no intake whatsoever haha.

Think XJ - remove stock exhaust go straight headers, and forget pods, run straight carbs no filter.

Yeah. LOUD.

 

dpawl. I would do the same thing I do with any other carb. Assuming it was setup properly turn the screws in to they lightly seat. Then write down the amount of turns. THen completely disassemble and clean the carbs. the idle screws could stay in there is not any air or fuel that goes threw there. But the air screw is like the idle mixture screw on our bikes and that circuit needs to be clean. That screw needs to come out and the passages clean. also make sure the fuel pump is working. the fuel pump gets fed off a pulse line that goes into the lower end of the engine and wroks on the vacuum. If that line is cracked anywhere the fuel pupm won't work. Easy test pull the line off from the carbs and pull over the motor see if gas comes out. On a sled that age i would replce all the fuel lines they aren't that expensive.

 

Man! That is some funny stuff! Thanks for sharing!!!

Loren

 

dpawl,

Here is a pretty good site you would probably have to go into the vintage forums, or possibly the zx ans earlier chassis section and post but the guys there should be able to help get you going.

www.dootalk.com

 

Ya know - I registered there last night. Said 10 minutes and I'd have an email to confirm so I can post. "Most are instant" instead of 10 minutes it said.

Didn't have ANY email from them... still don't. Hit BACK to make sure I put in the right email, and it's right.

BOO.

Anyway, I found the entire CLYMER manual for all Formula's 1990-1995 so at least I have that! But I am trying to get the DOOTALK going.

I joined on snowmobiles.com forums, and they were no help.
They don't care for anything that isn't 2005 or newer it seems.

I asked for a link to somewhere I can get detailed specs on the sleds weight etc, and what did I get? SKIDOO.COM.

Boneheads.

Hope dootalk sends me something soon... ugh.

But a 500 page clymer manual works! Especially for $2.98 direct download!