97 summit bog

hogwild · Oct 13, 2009

baught a 97 summit with 785 union bay engine, 46 mm carbs.it has a real bad bog from idle,1/4 throttle to full throttle is good. is this comon for these motors or should it be snappy. if i take revs up a bit then punch it all is good, if i just punch it from idle it bogs

Skidoohmx · Oct 14, 2009

I would check for sure that the carbs are opening at the same time. Does it idle fine but bogs when you snap the throttle quick? It maybe lean slightly at idle and need the air screw adjusted or a different pilot jet. The motor should be snappy right out of the hole.

hogwild · Oct 14, 2009

carbs are opening at the same time.yes idles fine but when i snap throttle it bogs,then pics up, it is snappy if i take rpms up a bit then snap throttle. how do i adjust air screw? 1 1/2 turns out?

Skidoohmx · Oct 16, 2009

I don't know what the exact setting would be for your airscrews but I would try turning them in a 1/2 turn if it gets better keep doing it until the bog is gone. If it gets worse go the other way until it is fixed. If it doesn't change then you may need to try different pilots or it is something else. Is yours a overbored 740 or a stroked 740 or do you know?

summit800 · Oct 16, 2009

you need to take the carbs off and check what size pilot jets are in them I think they were 75 on the 670 summits , also check float adj. Id ajust needle clip down 1 notch ,sounds like you might be lean on botton end if I remember right most 670 air/fuel screw were 3/4 to 1 out

sledsrock · Oct 16, 2009

Porting?

Has there been any porting done to the cases or cylinders?

hogwild · Oct 16, 2009

i just got this sled and as far as i know from what the guy told me,bored and stroked,fully ported,185 hpand massive torque,i am going to play with air screws a bit,also has them thunder dialajet things on the carbs were do i set them as a base line? i live at 2500 ft and ride up to 8000 ft.wich way is rich and lean on the air screws? sorry for all the questions

Skidoohmx · Oct 16, 2009

Air screw is richer turned in and leaner turned out. With your 46 carbs I bet it has 30-40 pilot jets in it. That motor should run real strong. You might want to do a compression check to see which domes are in it to ensure you don't have to run some higher octane fuel than pump gas.

DWHalverson · Oct 16, 2009

What kind of filters do you have on it? The rotary valved engines are very picky when it comes to filters. Twin pipes or single? I would guess either Crank Shop #10 twins or Jaws twins.

Dave

hogwild · Oct 16, 2009

crank shop twin pipes,no filters, i am going to order uni filters for it and biuld aluminum shroud to keep snow dust off. that was my plan anyway will it work? or should i use an air box

DWHalverson · Oct 16, 2009

STAY AWAY FROM THE UNI FILTERS!!!

Check your carbs and give this a try. This was for 6000' and up.
640-660 Mains
35 Pilot
7DH2 Needle
224-BB0 Needle jet
2.0 Slide
2 Turns out on the air screw
32:1 for oil

What do you run for clutches?

Dave

Thunderguy BOOSTED · Oct 16, 2009

oK all this talk about carb problems and no pics of the sled??? BOO HOO!!:beer;
I do know that me 97 740 UB with Crank shop twins and 45mm carbs has some crazy torque!! With the new P-85 clutch and the moded secondary and the kick a$$ air filters she's going to pull hard!!!! And now that i think about it, before i changed jets i did have a bit of a bogging problem too!! But after we put the small jets in it just came alive!

dont mean to be a thread highjacker or anything but i would like to no what i should run for jets? I live a 4360 feet and can ride right up to 10000 feet +! Right now i think i have a 230 and a 220!!! i think there a light small no?? I had a 360 and a 350 in there before!! And i only have the 4 setting vari-flow!( oh and just on another note the two lines going from my vari-flow to the carbs both had holes in them!!!! Oh i wonder why it ran like a piece of $hit last season! DUH!!!

Oh and also after a took it off the handle bar i looked in side of it and

there was a little seed stuck on the little pin inside!! (looked like a..... some kind of a wild flower seed!!:rose:

Any way!!

Iam ready to kick some a$$ this winter!! Who's with me???

TG

hogwild · Oct 17, 2009

heres a pic of the sled,mine has 390-410 jets in it. why not the uni filters?and what should i use then k&n?.why are these things jetted different on each carb? i could see it on the fan cooled motors but why liquid cooled. fans the are is colder coming in so one cylynder runs cooler, liquids should be the same. wont let me load pic look at s chassis mod pics

Skidoohmx · Oct 17, 2009

Dave has a very good setup that he stated above the only difference in my old modded twin was I ran main jets around 500-540. The mains you have are quite abit smaller but may be due to the fuel compensators. I know nothing about them.

hogwild · Oct 17, 2009

heres some pics

DWHalverson · Oct 17, 2009

Good news, bad news. Those are Crank Shop #10 stampings built to Simmons specs on the pipes. Very good pipes. Bad news is those are not OEM Ski-Doo 44mm carbs. The correct way to go to 46mm was with Crank Shop slides and a carb bore. You have Mikuni carbs and Mikuni slides. If they are bored out to 46mm you will have air flowing around the slide due to the large bore. You could take factory Ski-Doo 44mm carbs and bore them to 45.6mm if you were careful. The other thing is that Union Bay stopped building the big bores off the X/HO engine due to inconsistencies they found. You might be up against some of those too. I have a 740 I built off a 98 Summit X engine with the DPM still in working order and have had zero issues with it.

Dave

Thunderguy BOOSTED · Oct 17, 2009

Here's a question for you DWHalverson!! You know the line that go's to the crack case?( or did when they had the old H.A.C on it!) What do i do with that hole?? I dont think it should be open!!

Justin

hogwild · Oct 18, 2009

whats the deal with the filters?, i need to get some orderd but dont know wich way to go

Thunderguy BOOSTED · Oct 18, 2009

get the KICK A$$ 44mm air pods with pre-filters!!!

Are you in the US or CANADA??

Justin

hogwild · Oct 18, 2009

canada, east of calgary 1 hr

97 summit bog

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