polaris 250 engine

LarryG · #1 (**permalink**) 05-31-2010, 06:07 AM

I"m new to this forum. Thank you in advance for any help. My dad has a 91 Trail Boss. The engine wasn't running very good when the ATV was parked and has now been sitting for about 3 yrs. We're going to visit in about a month and it would be nice to get it running for the kids to ride. I have the opportunity to get an engine from an 87 Polaris cyclone. The engine runs but the transmission won't engage. My understanding is that this motor puts out more power than the newer 250's but I dont know if the engine is compatible with the 91 transmission or frame. Can anyone tell me what it would take to put this engine in the 91? We'll only be at my dads for two weeks and parts are difficult to get, so it needs to be pretty much a bolt in.
I can also get 250cc engines from newer polaris atv's very easily (1998-2006). Can anyone tell me what years of engines are compatible with this frame?
Thanks again. Larry

3 Polaris Atvs · #2 (**permalink**) 05-31-2010, 06:17 AM

A friend of mine installed a 2000 Trailblazer 250 in a 94 Trailboss. Bolted right in. He used the trail blazer carb.

**Bruce!** · #3 (**permalink**) 05-31-2010, 11:46 AM

Welcome to the board!

LarryG · #4 (**permalink**) 06-02-2010, 08:45 AM

Thanks for the response. That's what I'm looking at doing. Those era's of 250 engines aren't very hard to get around here. If anyone knows anything about 87 cyclones or 90-98 era trailboss and trailblazer engines I'd appreciate any info.

shane-o · #5 (**permalink**) 06-02-2010, 05:25 PM

i had an 87 ish cyclone and now have a 250 trail blazer a 2001 and they are very similer id use the jetting if not the whole carb if you decide to use the cyclone engine which i think would be a killer idea it has much more hp then my trailblazer in my opioion even if you could use the clutchs from the cyclone maybe a bit better clutching for that motor ?

LarryG · #6 (**permalink**) 06-04-2010, 06:42 AM

Thanks for the responses. This is what I"m going to try and do. If it doesnt' work out I'll look for a newer model engine. I'll let you know how it turns out.

shane-o · #7 (**permalink**) 06-08-2010, 03:33 PM

yah let us know im curious as to how it works out i dont think much changed engine wise except for carb cylinder porting and clutching so should be alright

LarryG · #8 (**permalink**) 03-18-2011, 06:55 AM

Ok, I'm long overdue to update this post. A move to alabama caused a big delay in this project, but it's going now. I got a complete and "sort of running" polaris cyclone. I also got a 2000 trailblazer that wasnt' running and had sat for a while for $400. Frame, plastics and transmission were all in good shape. The engine needs to be bored, but otherwise looks good.
The cyclone was a piece of crap. The transmission was destroyed. Has a big whole in the case where the gears siezed and exploded. The frame has a crack in it. Looks like it could be welded very easily, however I didn't want to mess with it because even brand new the suspension is nearly non-existant. Not a comfortable looking atv.
The engine ran and had 100 lbs of compression, but made a lot of noise. I took it to my mechanic and after taking it apart, he diagnosed all the bearings as completely shot. They fell apart when he took them out. The cylinder needed re-boring, but otherwise was in good shape. So, the engine is now complety rebuilt. All new bearings and seals, bored .03 over, wiseco piston, new rod, name it.
My 15 yr old son and I installed the engine in the trailblazer. It was a direct bolt in. At first I used the CDI from teh cyclone because the stator was the original from teh cyclone engine. The engine started right up, but after taking a couple fo trips up and down the driveway, the engine ate the entire stator adn wiring harness. I don't think my mechanic installed it correctly and the bolts came loose. Turns out the stator from the trailblazer engine is compatible with the cyclone engine. I installed it, used the trailblazer CDI and it started right up. The right side of the crank shaft adn pull start are different for the cyclone engine, but otherwise the engines are very similar.
We're in teh break-in process now, so riding it with only 1/2 throttle. I'm using the trailblazer exhaust for now, which doesnt' work worth a damn. The cyclone engine is ported way too high for the low revving exhaust of the trailblazer. I ordered an HPD trail pipe and clutch kit from Rick Ritter cycle. The HPD pipe will put out a lot more power than the stock cyclone exhaust and won't have to be modified to fit the trailblazer frame. He was real helpful and provided me with a lot of info. It turns out my stock cyclone clutch will allow the engine to rev to 7000 rpm. The main reason the cyclone made so much more power. Problem is that apparently these things went through top ends pretty quickly. That was the reason Polaris de-tuned them to 22 hp. The clutch kit is tuned for the exhaust and will turn the engine at 6600 rpm. I'm thinking that this, along with 100 octane gas will extend the life of the rings. From talking to Rick Ritter and the guys at HPD I can expect approx 39 horsepower.
Ok, once we get this thing broken in and the new pipe installed and tuned I'll update it on the actual performance.

RoosterTails · #9 (**permalink**) 03-18-2011, 06:59 AM

Sounds like a good father-son project! Good job!

shane-o · #10 (**permalink**) 03-18-2011, 01:37 PM

im glad it has all worked out for yah that thing should move pretty good wiuth the right pipe and clutching !!!!! any pic of the finished product?!!!!