Trail Blazer performance mods

[Rockwerx]

Anyone mod their Blazer? They don't make them any more but they were a fun little quad.

I am curious if they had different CDI boxes that had a different rpm limiter. My son's 2004 model does not seem to rev as high as the old 98 we had. I changed to a larger rear sprocket and it gave it a bit more bottom end, but it still does not seem to run as strong as our old one. I am also looking for the air box from a 2002 quad to put into his 2004.

Polaris used the same or similar engines in a few other models like the Explorer and the Trail Boss, so I believe that the same mods would work for many of these engines. I read that you can also install a larger cylinder, piston and head off a 300 or the 350 of some model. Not sure which models to look for parts though.

 

[mike h]

I had a 98 trail blazer. Used all HPD, pipe ,clutch ket, and trail porting, head was shaved 25 thousands i believe. great low end. Would run 58mph by my gps. Also look at Aaen performance or Hot Seat. I have used both I like HPD the best got more bang for the buck.

 

[Rockwerx]

I had a 98 trail blazer. Used all HPD, pipe ,clutch ket, and trail porting, head was shaved 25 thousands i believe. great low end. Would run 58mph by my gps. Also look at Aaen performance or Hot Seat. I have used both I like HPD the best got more bang for the buck.

Thanks Mike!

That sounds like a fun combination of parts and modifications. Where did you get your porting done? Did you have to run race fuel or just premium pump gas?

I am still wondering if the CDI box is limiting the potential of the 2004 engine. I have not found any info on the CDI box at Aaen or Hot Seat.

I found a used pipe for it and may purchase it.

I will update this post as I modify the quad so others may learn how to have some fun with these machines.

 

[mike h]

I got the porting done at hot seat.along with shaving the head. Also had the flywheel cut at hot seat had alot faster rev. I ran 93 octane never had a problem. Ran 110 octane didn't feel any difference no need to spend the extra money for 110. I don't think the CDI box will do anything. The rpm is controlled by the spring and weights in the front clutch. What i did when the my bike was stock was put a stock 400 sport spring in the front clutch. Gave the bike more stall. Also if u could find a 34mm carb off of a 400 sport it would help alot on a stock machine. I was running a 38mm had no problems but i had alot of work done.

 

[Rockwerx]

I got the porting done at hot seat.along with shaving the head. Also had the flywheel cut at hot seat had alot faster rev. I ran 93 octane never had a problem. Ran 110 octane didn't feel any difference no need to spend the extra money for 110. I don't think the CDI box will do anything. The rpm is controlled by the spring and weights in the front clutch. What i did when the my bike was stock was put a stock 400 sport spring in the front clutch. Gave the bike more stall. Also if u could find a 34mm carb off of a 400 sport it would help alot on a stock machine. I was running a 38mm had no problems but i had alot of work done.

Thanks again Mike! Good to find out that there is not a rpm limiter built into the rev box. It sounds like you went all out with your mods! I am not sure how far I will take ours yet.

Did a compression test and ours is a bit low I believe...around 115 psi. My last one was around 130 psi as I recall. I am going to pull the pipe to check the condition of the piston and cylinder wall. If there are any visual clues like obvious piston damage I may have to bore it and replace the piston and rings.

 

[mike h]

You may need to rering the piston. Are u still oil injected? If so keep a close eye on water in the oil tank. I lost 2 motors before i found the problem

 

[Rockwerx]

Still oil injected. So far we have not had any problems with water getting into the oil tank. It uses very little oil, but I always keep it topped up.

I am going to put a new piston into it. There is no damage on the exhaust side but there is some streaking on the intake side on the piston skirt. It looks just like a snowmobile piston that was injesting some snow dust. It may have taken in some water at one point but there was no evidence of that in the air box or air cleaner (paper filters usually distort when they get wet). It could have also been caused by a stuck float in the carb. It was running extremely rich shortly after we got it...might have damaged it then.

 

[mike h]

Sounds good you may want to look at a uni air filter that is what i run. Works great and they are washable.

 

[Rockwerx]

Sounds good you may want to look at a uni air filter that is what i run. Works great and they are washable.

What are you running for a quad now?

Did a bit of light porting on the cylinder. Basically cleaned up any rough castings, polished the exhaust port and raised the exhaust port slightly. Shaved the head .002". I am running a 140 jet so it may be a bit too rich but I will start with that and see how it runs.

 

[mike h]

I have a 05 honda 500 rubicon 2in lift,jet kit,other than that it is stock. Also have a 400 polaris scrambler 2x4. HPD trail porting,head shaved,pipe,cluch kit,team roller rear clutch, 39mm carb,1 1/2 inch front wheel spacers, and a 2 inch dura blue axle. Love my polaris.

 

[Rockwerx]

I bet that your Scrambler is a lot of fun...especially with those mods! I wish I had purchased a 4x4 Scrambler instead of the Sportsman...she started giving me grief after around 1500 miles.

Okay, the quad runs pretty good now that she has a new piston! I am going to jet it down after we burn a tank of fuel through it. I also picked up a used (but like new) DG pipe and will put it on in a few days. Yee haa!

Funny coincidence...my brother...who lives a few hours away...bought a used 2002 Trail Blazer. They went out to test it west of Calgary at Mclean Creek...it had snowed about a foot but they went ripping anyway...one of their quads has 4x4 and a winch so they were not afraid of getting the little quad stuck. By the end of their ride the Trail Blazer would hardley run though. Very low compression.

So he picked up some standard size rings for it. I always tear them down before picking up parts. He should have done the same. I spoke with him last night on the phone and things did not add up. The rings he picked up were a lot thicker than the ring grooves on his piston. Also, when I asked him to position a ring into the bore to measure the ring end gap the gap was too much for a standard size cylinder bore...it had been bored for a larger piston. I asked him to dust off the carbon on the piston dome...it is a Wiesco piston...just like the one I just installed. So he has to get different rings of course.

While I was on the phone I walked him through the work for polishing up the exhaust ports. He found some casting imperfections that he removed with a dremel tool. Mine was similar by the sounds of it. I told him to not do any porting if he did not know what to do...if he wants more power later I told him that I could do it another day.

Anycase, now I have to make mine go faster and quicker than his! lol I have a few tricks up my sleeve so I am not too worried! My new pipe should add 1-3 hp...my lower gearing should give mine a head start but may kill my top end speed. Hopefully my light porting job and shaved head will also give me the advantage. If I can not beat his quad then I am going to try some different shift weights and/or a different spring in the clutch. I may look for a larger carb also.

I will keep updating this thread over the next few weeks or over the summer for anyone else who is interested. If anyone needs any help with thier mods I am willing to give my advice.

 

[mike h]

I also had a DG pipe for my 250 very loud could not tell any performance gain. But that was when they first made a pipe for the polaris 250. I'm sure they make a better pipe for the 250 now.

 

[Rockwerx]

Someone installed a standard size Wiesco piston into his Blazer. Usually you have to bore the cylinder and go up a size. Anyway, he ordered the correct rings but they won't be in for a week or so. It will be awhile before we can race so I have some time to do some tuning now.

The new pipe added some mid and top end torque. Maybe 3 hp? They advertized 3-5 hp increase so I expected 1-3 with the minor mods so far.

I may try some lighter clutch weights after I jet it down. I still want to be able to trail ride it so I am not trying to build it too wild. So far so good!

 

[mike h]

If you are still running the stock weights in the front and the stock springs in front and back clutches you may want to look for a clutch kit that has weights and springs. That way you will have a match set, and you will not have to play with different weight and spring combinations the work will all ready be done with a kit. Also cheak your belt free play. As the belt wears you will have to adjust the rear clutch with shimmes to have the max performance and belt life. Another trick you could do to stay infront of your brother is to by a clutch alinement tool. From the factory the clutches will not be alined properly for max HP. This trick will keep you alittle bit ahead of your compitition.........Good luck!!!!!!!!

 

[Rockwerx]

If you are still running the stock weights in the front and the stock springs in front and back clutches you may want to look for a clutch kit that has weights and springs. That way you will have a match set, and you will not have to play with different weight and spring combinations the work will all ready be done with a kit. Also cheak your belt free play. As the belt wears you will have to adjust the rear clutch with shimmes to have the max performance and belt life. Another trick you could do to stay infront of your brother is to by a clutch alinement tool. From the factory the clutches will not be alined properly for max HP. This trick will keep you alittle bit ahead of your compitition.........Good luck!!!!!!!!

Sounds like good advice Mike! If I am not happy with my own tuning I may look into purchasing a kit. I wonder if the alignment tool is the same as the one for the sleds? I will find out.

I am not exactly sure what springs and weights are in the quad. Shortly after I purchased this quad the dealer was helping us tune it and they either changed a spring or changed the shift weights. It made it a little bit more spunky off the bottom end so I believe they only changed the primary spring.

When I started to add more power to my sled engines I found I had to add heavier and even heavier shift weights to keep the engine from over reving. In the case of the 250 it may have too heavy shift weights from the get go...maybe lighter weights will let it rev up more.

This will be a good time to check the condition of the clutches, fly weights and belt. I will also clean everything as belt dust is very hard on some of the small parts. I learned to keep the shift weight bushings clean in my sleds the hard way. The bushing in the shift weights wear and then they start to go out of alignment, then they start cutting into the central hub...destroying it in the process. Mind you this engine does not put out the 150-220 hp that my sleds produce so wear and tear is not near as severe.

 

[mike h]

I don't know anything about sleds but by the way you talk they are about the same. Sounds to me you are on the right track. I have a few more tricks but i think you know more than i do. Keep me updated. It's nice to talk to someone that likes there polaris as much as i do!!!!!!!

 

[Rockwerx]

I do love my Polaris machines! I have been building up my own sleds and engines for many years now. Still learning new things all the time though. I am thinking that my Blazer has the same clutches (or at least the same primary) as our old 95 Supersport 440 sled. So maybe the same clutch alignment tool will work on the quad/quads?

I am still wondering if the little 250 engine will make more power and go faster with lighter shift weights. When you increase the power in the sled engines you have to add more weight to keep the engine from over reving and also to keep in it's power (actually torque) band. You can achieve this in a combination of ways. You make it upshift faster to put more load on the engine and/or you can gear it up by changing gears in the chaincase to put more load on the engine also.

For instance when my RMK 800 was stock it would pull 60s here on the prairie but running it in the mountains it could only pull 60s on the super cold days so I would have to use some 58s in the higher altitudes. My modified UB950 engine will pull 76s on the prairie...not sure how much weight it will pull in the mountains yet.

Back to the Blazer. The little engine will not rev very high in stock form or with my mods so farso I don't believe it will hurt it to make it rev up 1000 rpm or so more. I am going to try some lighter shift weights to see how it performs.

Anyone else reading this thread can chime in anytime if they would like to add something of relevance so we may all learn more.

 

[mike h]

When i put a HPD pipe and clutch kit it gave me around 1000 more rpms and alot of power. I cann't remember what size the weights were but i do know that the front spring was brown and the rear spring was white i think. My buddy still has the bike i could find out. Look around and try to find a 1988 250 6x6 cylinder. The ports in that cylinder are huge compared to the ports in the newer 250. I found one and still have it. Bolted up to my 98 250 sould work on yours.

 

[Rockwerx]

When i put a HPD pipe and clutch kit it gave me around 1000 more rpms and alot of power. I cann't remember what size the weights were but i do know that the front spring was brown and the rear spring was white i think. My buddy still has the bike i could find out. Look around and try to find a 1988 250 6x6 cylinder. The ports in that cylinder are huge compared to the ports in the newer 250. I found one and still have it. Bolted up to my 98 250 sould work on yours.

That would be excellent to find out what weights and clutch springs are in your old machine. Don't go out of your way to find this out but maybe when your friend services his clutches you could find out then.

I was reading that the older cylinders had better porting than the newer ones. That may explain one reason why our old 98 model went quite a bit better than the 04 model. I would still be running our 98 but some criminals stole it from us when we were out camping.

I did not know they made a 250 6x6 even. How much are cylinders like yours worth? Does it require a different head?

Did some more research into installing a larger piston and cylinder off a 300 but they also run a longer stroke crankshaft...not very cost effective mod at this point. Maybe if I was at the point of rebuilding the engine it would be a good mod.

People sure under estimate these quads...you would not believe where we have gone with ours! Many times I have been the first to the top of mountains...on the smallest and lightest quad in our group. :d

 

[mike h]

I will try to get the weight size for you. What i understand is that the older bikes had to make more hp because polaris was refineing the pitch on the clutches. So if you had a older 250 you would put the newer clutches on the bike. I did it with my 98. I put 2001 clutches on it front and back. As far as the 250 6x6 that is what i was told the cylinder came off of. The guy i got the cylinder from was a polaris machnic so i took his word for it. He also told me HPD offered him some money for it but he never said how much. The cylinder and head are the same on all 250's that i have seen. Bolted on mine with no problem.