TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: tlr7272 on November 25, 2014, 03:47:28 PM
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I AM DOING A TOTAL BUILD ON AN 86 250R .... MY INTENTION IS TO BUILD A 50 hp plus woods quad..... I have boughy many of them but this is WAY different I just purchased an 86 cylinder that has been mx ported and polished and I have a 38 mm airstryker carb with v-force 3 reeds... so with that said am I even in the right direction??? what should I do to bottom end ??? long rod short rod stroker ??? IDK???? it has to be reliable SO COULD SOMEONE PLEASE DIRECT ME THE RIGHT WAY!!!! and since im going to b in the bottom anyway should I put a better clutch in it??? aAlso the dome should I put a cool head on it or what should I use.....???? what about the electronics ???? thank you to anyone who helps cause im trying to get the motor wrapped up so I can move onto shocks,a-arms ,steering stem axle , sprockets the list goes on..... thank u
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We have all told you our opinions on this. You should look ath the previous threads that you have created. All the answers are in there.
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that's impossible I just purchased cylinder??????????/ but that's okay il FIND OUT SOMEWAY!! BUT THANK YOU GLAD U SET
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If you purchases a cylinder that was already ported, you have to use a crank that it was setup for. You can't simply use a +4mm crank
Find out what crank the cylinder was originally used for.....was it a spacer plate cylinder?
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:carlos::carlos::carlos:
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I AM DOING A TOTAL BUILD ON AN 86 250R .... MY INTENTION IS TO BUILD A 50 hp plus woods quad..... I have boughy many of them but this is WAY different I just purchased an 86 cylinder that has been mx ported and polished and I have a 38 mm airstryker carb with v-force 3 reeds... so with that said am I even in the right direction??? what should I do to bottom end ??? long rod short rod stroker ??? IDK???? it has to be reliable SO COULD SOMEONE PLEASE DIRECT ME THE RIGHT WAY!!!! and since im going to b in the bottom anyway should I put a better clutch in it??? aAlso the dome should I put a cool head on it or what should I use.....???? what about the electronics ???? thank you to anyone who helps cause im trying to get the motor wrapped up so I can move onto shocks,a-arms ,steering stem axle , sprockets the list goes on..... thank u
You are going to need and engine/displacement much larger than what you can make from an OEM 86 cylinder to get 50 hp plus (on my dyno). A 50 plus hp 250 is not going to be a woods quads nor will it use that small of a carburetor, nor is it going to be reliable and be easy to tune and run on pump gas.
I think that you need to lower your hp goals to around 40 hp to meet your reliability expectations with the components you have on hand or you are going to need get the check book out and start over.
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Well said Jerry. Over expectation runs very high with our new members/builders
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ok that is very helpful so I should ask guy what it vame off???? thank u VERY MUCH
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so do u think I got screwed on 86 cylinder that's been sent to esr for mx port, I paid 150 hes said he was running v force 2 and 39mm carb and he had 50 plus horses mayb cr ign tooo IDK......what do u think is it realistic
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its cool I got check booook and I could go buy a 20,000 quad for 6to7 all day im just passing time and I guess it will b trial and error ...not a life ender.... but thanks for imput all of it goes somewhere
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its all about something different 40 hp 450s are a dime a dozen and actuyally boring but im sure I will come across the right setup to beat a 450 threw the woods or track ... im positive of that
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so do u think I got screwed on 86 cylinder that's been sent to esr for mx port, I paid 150 hes said he was running v force 2 and 39mm carb and he had 50 plus horses mayb cr ign tooo IDK......what do u think is it realistic
He was blowing smoke up your arse when he claimed it made 50hp with that combo. OEM cylinders can be made to run very well but the only way you can get strong bottom end grunt & screaming top end performance is with a big bore. With an OEM small bore cylinder you'll generally get one or the other.
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so do u think I got screwed on 86 cylinder that's been sent to esr for mx port, I paid 150 hes said he was running v force 2 and 39mm carb and he had 50 plus horses mayb cr ign tooo IDK......what do u think is it realistic
Building a 250cc engine package around 55 hp (not a big bore in an OEM casting) is easily attainable when the engine is put into the hands of certain builders, but it is not going to be a good woods bike. These engines can be used effectively on an outdoor MX track in the hands of a small number of pro riders.
I recommend that my customers replace the pistons in their 50 to 55 hp 250s used for mx at least every 5 hours or less. These engines will start showing a power decline at about 2 to 3 hours of hard riding without being on the verge of catastrophic failure.
Shifter karts with 250s making well over 60 hp will start showing a power decline at around 1 1/2 hours of hard usage and need pistons every 2 to 3 hours.
The definition of realistic or practical is totally different for different engine owners. Guys that are running 70 hp 250s in their micro-sprints cars spend the money to replace the necessary parts on a weekly basis if they are highly competitive. The expense to maintain engines of this caliber is realistic and necessary for some guys but not practical or affordable for the average recreational rider trying to use an engine of this caliber for a weekend of recreational riding.
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It's difficult enough to find a builder who will take the time to do a thorough, detailed job and make a reliable engine to order with solid recreational performance.
Finding one who will make the power you're talking about without scamming you requires a select qualified builder, likely who has worked with professional racers and packs a database of years worth of precision technical findings on precision instruments. I am not in the later camp, but the more challenging things to me about providing honest engine design services was helping people not underestimate what it takes to build to what expectation and how that effects their budget.
Jerry is in this later camp. Most people who will encounter him online in a forum will not grasp how much difference there is between what that type of builder understands from most other builders.
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what you have working against you is the non-variable exh port. without this feature your stuck between a rock and a hard place. from my experience working with nonpowervalve stuff is your always going to be making a compromise how well the engine performs in a desired rpm range
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so will it b a good woods bike with just esr mx ported cylinder,38 mm carb with vforce 3 and dyna cdi box and fatty fmf w fmf silencer, 450 shocks on front............the one thing I know it will b reliable and should keep up with pipe 450s in the woods........I hope.. ok so tell me do I want powervalve?? stroker, welded crank? what kind of cylinder like I said I don't need that wide open desert hp I just thought 50hp was realistic my friend swears his 450rputts 50 dowb and bhe only has hrc kit he claims.......thisb is my first project so if something id
s dumb as hell its just someone wantinh to learn .................thank u udontknowme
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I understand that ,,,,but if I know something and someone is asking question and I know I can help him I WOULD ITS FREE IT DONT COST ME ANYTHING TO POINT SOMEONE INTHE RIGHT DIRECTION........... but I guess knowledge is power and it goes to ur head cause I guarantee he asked questions even if it was 20 years ago...........I guess to each there own I woulg tell it like it is...................
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I don't see what the problem is, EXCEPT that a 50hp woods friendly OEM 250cc jug pump gas motor isn't possible. I have a 50hp oem jug and it isn't a woods motor. It's a peaky screamer(and was built to be that-no it's not a drag motor btw). Everyone here has no problem sharing info btw.
To get that kind of hp out of a stock jug, EVERYTHING must me matched up to compliment each other and not just a pile of parts thrown together.
The other thing I think you're leaving out of all this is the rider. IDK how well you can ride, but the rider will be one of the most important parts of this machine. A great rider can easily overcome being down a few hp by riding both harder and smarter.
I'm sorry if you didn't like the answers that others have given you, but they are honest answers. Would you rather have a builder lie to you and then be disappointed?
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You'd have to be an excellent woods rider to keep up with built 450 quads on a stock 250r cylinder. You would have to ride virtually mistake free.
You need to go to a 330cc or bigger cylinder, depending on how much you weigh and your skill level
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A stock off the show room floor TRX450 will make 36 to 37 hp to the rear wheels on my dyno. Remove the air box lid and rejetting the carb will raise the power to 38 to 40. Add the best exhaust pipe and muffler on the market to the stock engine with the air box lid removed and the pipe will add another 1 to 2 hp. Now install the full HRC kit to the engine with the air box lid removed, the best pipe and muffler and now the kitted motor will make 43 to 45 hp on my dyno. Do the correct things to the ports, valve seats, and valves and now the 43 to 45 hp package will make 49 to 50 on my dyno making 8 to 10 second long dyno runs.
An off the show room floor YZF450 Yamaha starts off at 37 to 38 and responds very similar to the same modifications/external bolt ons as the TRX450, but will end up at about 46 with the air box lid removed, rejetted carb, best pipe and muffler on the market, and exhaust cam retarded 1 tooth.
A LTR 450 Suzuki off the show room floor will make 40 to 42 off the show room floor and make 48 with the air box lid removed, best pipe and muffler, and the fuel map re-mapped.
four-strokes typically have a higher power average over a wider RPM range than two-strokes. It will typically take a 53 to 55 plus peak hp two stroke to beat or run equal in a drag race to a 50 HP four-stroke.
I cannot say your engine will not make 50 hp on someone elses dyno without knowing their dyno testing procedures, type of dyno, what was done to the ports, combustion chamber and what pipe they were using. I can say it has been my experience that I have not see a 50 hp 250 on my dyno that I would consider to have the shape power band that I would consider to be good for woods riding.
We dyno a lot of ATVs, UTVs, motorcycles and street hot rods where the owners are really disappointed with their recent vehicle purchase, or their self selected mail order engine components or some professionally built engines. Talk is cheap in the forums, advertisements and bench racing sessions. The race track, or dyno and or lining up side by side will reveal the truth.
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i think if i were you i would look into a 72 bore puma. take your oem crank and weld the tins on. i dont see how you could go wrong with this setup and it wouldnt cost all that much
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I have seen certain builders claim to make big numbers but would not put much trust in people that have to toot their own horns constantly. Jerry and others have taken time to give good and honest advise. I value this and you should also.
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ya seems like dyno keyboard racing is all to common anymore. banshee sites are the worst :glee: