Has anyone ever used or heard of anyone using the race logic sport port template? I have seen there stuff on ebay and went to there website, it sounds good, just looking for some first hand experiance. I am trying to stay away from the puppy shops.

88 lt500 V-FORCE REEDS, FMF PIPE, 39 PWK, K-N FILTER, (Looking for a LRD pipe)

 

I'm sorry, I can't help, I have no first hand experience with them. I was thinking about them a long time ago for snowmobiles, I never got around to it.
However, since you sound like you are going to do your own building maybe we can throw some ideas around on here. I've read a few posts lately that sounds like we might have some tuners on here. Between all of us maybe we can come up with some cool ideas; port heights, durability, etc. If not, at least its fun to talk about 500 two strokes.
What do you say guys? Should we get in to it? I'm not talking about bolting on a stage kit and pipe and going 108 mph next to yor buddys civic. I mean talking about ideas that we've tried or thought about to make power.

 

Hi guy's!

I haven't personally been around the race logic template stuff, but have read their advertisement...Sounds pretty good, but ????? Sorry I'm no help with that one.

I've got some pretty wild ideas about port specs, etc. for the 500's... mostly stuff I've experimented with or wanted to try. Even played with design software a little.
Seems there's a BUNCH of things that can be done to the antiques to really make 'em run.

Regards

 

Duneaddict, I'm curious to hear what other tuners would like to do to the LT. Maybe others will join in later. I come from snowmobile tuning so atvs were a bit of a power band learning curve for me.
I guess I'll tip my hand first. I liked the 500 bottom end power but it had a hard time running with the more efficient twins ( you know what I mean, no names). I realized how much it came around with widening the exhaust port; so how do we make it bigger? I decided to put in triple exhaust ports. At the same time I put in a guillotine type power valve. This would let me keep my beloved bottom end and now should let me enjoy some top end. With this added exhaust area I welded on a '87 size reed cage and used V-Force reeds.
Now as long as I was going to do all of this work, I figured I would try and fix some of the reliability problems people complain about. First was the main bearings wearing out the cases. My thought was that the rod pin was too small and the crank was "wiggling" (just like harleys do). I went from a 24 mm pin to a 26mm pin. Next was cooling. Every 2 stroke suffers from that. I put in a Nicasil plated aluminum bore. I used my stock head but o-ringed it.
This all worked real nice but the pipe I made for it revs past 8500. It makes power at 6800 like it should but over revs way way way too high. I need to fix that or if I'm not carefull I will hurt it. I rolled up some more cones but I never fit them to the quad yet.
This is a bit of work to do to a motor. I would hope there is a better way. I hate to say it but I think 500 cc's is too big for one cylinder. It don't have enough time to fill it's self. Anybody have any ideas?

 

Wow Halfliter, you've invested some time in that bike! I'm wondering if you created intake ports in the piston. Also, what piston metal is preferrable for what use. I'm thinking a full bore drag bike would need a forged piston for it's strenth, but a cast piston might be lighter and sufficiently durable for most of us. Would it be wise to port both types of pistons or is a cast piston prone to crack due to the weaker metal?

 

Holy Cow Halfliter, you've spent some serious time 'building' your own setup.. Sounds like you are much more of a fabricator than I am.
Wow, you'd better watch that over-rev! Per the TSR software, terminal velocity for a forged piston that big is right around 7,500RPM... I've got mine set up to drop off at 7K..
Cooling is a big issue, and a major contributor to premature death. A temp gage is a must! along with a few other tricks to help out...
Detonation is another big killer on these tanks.
The idea of a 3 port exhaust (New cylinder casting) has always intrigued me, along with a 10mm longer rod, and a 92.25mm KTM SX piston.... This combo with some very agressive porting and perhaps some 'chemical' engineering should be a very capable at handling the 'twin cylinder' crowd.
Way too much $$$ for me however, as I am on a very limited budget.

My most recent 'conservative' build was all generated from TSR software, right down to the pipe (You can see pictures of it on my photo page). It's a very potent combination, and should prove to be reliable. But... It doesn't run hard enough! It has monster mid range, but still not enough..
Of course I started with the large reed '87 cylinder, but used 3/8" NF head studs to stop the little problem with studs pulling. I run the stock reed cage with a good carbon fiber petal, 42mm PWK, 185# Static compression, 114 octane fuel.
I'll agree with you on the crank issues... It's very cheap insurance to TIG a bead around the pin to help stop that nonsense. Steel (Not bronze) bushings in the case are also the best fix.

I'm building a hybrid machine right now (If you see any spare '87 motors laying around, I'd buy it!)
Another big problem with the mighty 500 is they are too heavy to be really fast! The hybrid should be around 265# when completed....
A good friend of mine has been letting me in on a few 'speed'/black book secrets, and my next motor build will be by his specs... even though they 'break' some rules. (E.G. Exhaust port wider than 70% bore diameter, etc.) ((He's a past SCR R&D guy))

Check this out: Exhaust, 40.5mm High X 62mm at the bottom tapered to 66mm at the top at 190 degrees (Trapezoidal)
Transfers, 19mm High +1.5mm wider at 129 degrees
Intake (X2), 32mm wide and lower by 4mm
Sub Intake, Raise 2mm & 6mm radius

Those are huge changes over stock configurations... I'm really anxious to try this out on my drag/hybrid... I'll make up for any shortfalls with chemical engineering (Blue bottle)
44mm carb bored to 46mm, ceramic coat piston top, and do some grinding on the piston too (Can't buy a good piston without improving the flow characteristics a great deal..

He swears by the reliability of this setup and with the use of very generous radii, the 70% rule can be 'cheated'. I can't wait to get this one put together to find out.

Yes, VegasQR... Piston porting can improve flow tremendously... I wouldn't use anything but a forged wiseco if you plan on doing some grinding.... also, the bigger bore pistons (88mm +) the dome needs milled at 15 degrees all the way to the outer edge (Wiseco flattens out)... This along with a properly set-up head will help with the detonation prone motor.

I still suffer from the theory that 'there's no replacement for displacement'... I'm convinced that once opened up to breathe like it should, it should run more like a 500 is supposed to.

Hey, since you're a sled guy Halfliter, would you have any specs for a yammie triple? 700MM is what I'm tinkering with, and would love to get my grinder into those ports.... just hate the thought of doing 3 of them!

 

First, about porting pistons. I only had to do it to a couple of motors. I used both forged and cast. I never had a porting related problem. I only use a Wiseco piston if I can't find a OEM cast piston to work. They are just too soft and grow way too much. Plus the skirts sag. Personally I like to stay with cast.
I use a cast piston from a KX 500 in my LT. The piston is stock with no porting. As stated before, it's been over revved and it's working fine. I have about 3 years on it. It's past due for replacement I know. I did want my pipe to shut off at about 7500 but I made it too short. Part of the atv learning curve.
Duneaddict, your port specs sound pretty wild. I'm not saying they are wrong, they just sound aggressive. I've only built one big bore (a couple of different configurations) and it was built for trail riding. I wanted range. Your going to have more compression and displacement so I'm curious how that combo will work. The pipe I have on my quad would match real well with your exhaust port[img]i/expressions/face-icon-small-smile.gif[/img]
My transfers are real close to stock height but staggered 1mm. They are widened quite a bit. The exhaust port is at 165 degrees with valve closed and 190 open. I don't know the exact % of bore wide but the triples are all the way to the wrist pin bore. I've run single exhaust port motors at 72% with no problem at all. I think the key is nice chamfers and radius. Plus it sounds like you know the right shape.
My carb is the stock one and only bored to 39.5mm. I only wanted to make power at 6300 and rev to 7500. I thought that would have been big enough. It sounds like everyone else runs way bigger. Something for me to consider.
My opinion on "no repacement for dispacement" is the 500cc single just don't have time to fill it's self with air. We need more time area on the transfers. We can do that a few different ways. One is stroke. That means even more piston speed. Bad. Higher transfers. Too peaky. I went for the longer rod. That alows the piston to sit at bottom dead center longer. More time area. The down side is more time at top dead center. Bad for detonation. I think what we need is something to force the air in. Like a cool turbo. Or four 125cc cylinders spinning in perfect harmony at 16000. Now we are talking some real money (sounds like some guys on this forum can't spend enough). By the way, my whole motor project only costed about $1000. Most of that was welding and heat treating costs. My friend bought his own tig welder now so we won't have as big of a welding bill.
I do like the feel of the big bore so I guess thats why we do what we do. One nice thing about having only one cylinder is that we have all the outside transfer room we need. I laugh at the twin guys when they big bore theirs. Where do they find transfer room to feed an even bigger bore? My friend wanted his Banshee big bored. We decided to put two Yamaha V-Max 4 cylindes on it. They are a ton wider than those baby Banshee cylinders.
About your 700. My girlfriend had the 700 SX. We got that over the 600 because it was a triple and had exhaust sub ports. I figured better mods. She wouldn't let me touch it. In fact, she put paint on the head nuts so I wouldn't take it apart! I personally never done anything with them. I hear they respond well to big bore. I don't know how, they are pretty small. Also when we develop a multiple cylinder motor on the dyno we use a single cylinder version. We learned that tuning V-Max 4's. Four cylinders, pipes, carbs, detoed pistons......

 

I'll agree with you on the forged vs cast piston debate... My theory has always been, i'd rather have something bent than something broken... I've had a few cast pistons crack/break skirts, etc. But I've also had a few forged pistons collapse... We have to choose our own poison I guess. I watch mine very closely, and as soon as I notice much distortion... time for a new piston.

Yes, my specs are VERY agressive, and more for a drag/sand dune play motor than a trail/woods type setup. The general theory with the higher compression is to help regain some of the lost low end power with the radical porting.. I'm with you on the transfers delivering enough to feed that big bore... and that's where I'm skeptical with these agressive specs... Can the transfers really feed an exhaust port that big? A turbo would be a fun experiement!! I'll be building it soon, so hopefully will have some real seat of the pants testing before winter.

I would be willing to bet you'd be happy with a carb upgrade... there is such a thing as too much. I started tinkering with a VM44, and it was too much carb for a stock cylinder... IT still helped it on the big end over the stock carb, but lost way too much throttle response. The taperbored PWK works VERY well with a moderately ported motor... Great throttle response, very crisp, and decent top end. For my wild drag motor, I'll run a whopper carb to feed those ports, because top end will be all I care about.

It's been great visiting about different ideas.... Always a learning experience!
That Exhaust set up of yours sounds pretty wild... I'd like to see a picture of that!

 

Sounds like some of these porting specs are from DR.Q on macdizzy.com. You might want to check it out. If you need any help with that lt250/500 email. I might be able to help. I have a 92 lt250 with a 500 motor. I did tons of research before I did it. Mine been working great for two years now.

 

That's exactly where they came from Jason! The Doc is a good friend of mine, and I'm quite anxious to get these specs into a viable candidate as they are much more aggressive than my first build on my 500. (I'm still shopping for a basket-case motor to start the build with)
He's given me some really wild ideas, and some renewed faith in the hybrids.

I'd be very curious as to how things went for you on the install... Especially with the rear sprocket mis-alignment, and how you corrected that one. Otherwise, I think it's going to be fairly straight foreward.
Doc claims that the 250 Radiator is sufficient... What are you running?
Did you custom build your own pipe?

I'm working on building an all aluminum sub-frame, new A-arms for the '85 chassis....
I'm hoping for around 10" travel front and rear...