Tri Z Engine Build

[onformula1]

Yep, 38 PKW. Blue "JD" needle from a 250 KTM, #7 slide, pod filter, stock steel reeds, float height at 16mm and 1.5 out on the air screw to start. She came off the choke pretty fast and smoked pretty heavy when warm. It sings up super fast from idle, but starts to blubber a fair bit as she nears the top. In saying that it sure seems to rev a lot higher than it used to. The thing sounds more like a 125 that a 250 when the throttle is stabbed in neutral. I love it!

Stock steel reeds???

They were bad in 1985...

[onformula1]

Yea, it's a 99.99% done deal ( I hate saying 100% in case something comes up). I had planned to go this year, but totally screwed up the date when coordinating a trip my wife was planning and told her to buy her tickets for the day TF 2015 was ending Given the rain I guess I was lucky. Anyway, I won't make that mistake for 2016. Really looking forward to it Planning to bring 2 trikes, 1 big bottle of rum and a 1/2 dozen cigars. Food, shelter and other luxuries I'll figure out when I get there. Slept in my truck cab for three seasons of drag racing, I can do it again for one week.

I would love to go to trikefest, 26 hours one way is a long drive!

[El Camexican]

I would love to go to trikefest, 26 hours one way is a long drive!

Longer for me I think.

Yea, went with steel reeds for the stiffness hoping to get a few more RPM out of the engine. The stops are opened to as large as the cylinder will allow. I have a set of Boyesen's but want to try the steels first.

[onformula1]

Longer for me I think.

Yea, went with steel reeds for the stiffness hoping to get a few more RPM out of the engine. The stops are opened to as large as the cylinder will allow. I have a set of Boyesen's but want to try the steels first.

The steel reeds will flutter before you ever see any of the new found power from mid to top.

[El Camexican]

The steel reeds will flutter before you ever see any of the new found power from mid to top.

Good point. They will get one test before the fibers go back in.

[onformula1]

Good point. They will get one test before the fibers go back in.

They will be much better and will not flutter, but they will float a bit.

In the end I will predict you will end up with carbon fiber high tension reeds.

[El Camexican]

They will be much better and will not flutter, but they will float a bit.

In the end I will predict you will end up with carbon fiber high tension reeds.

I think that would require the V-Force set-up. I was really hoping to avoid that. Do you know of a CF reed that fits the stock Tri-Z cage?

[onformula1]

I think that would require the V-Force set-up. I was really hoping to avoid that. Do you know of a CF reed that fits the stock Tri-Z cage?

Carbon Tech reeds-

http://www.carbontech.com/motor/yamaha.html

88-92 YZ125 part number- 144HT (Same as a Tri-Z) $54.95

I like this set-up over the V-Force, less money too.

[onformula1]

You could use Boyesen carbon fiber reeds for the same application if you want, I like the Carbon Tech reeds better and have been using them since 1993, what's interesting is Boyesen is now selling Carbon Tech reeds on their website, that seems a bit strange to me?

[cr480r]

Still some tdr carbons out there floating around. I have a set in mine. Got em for like $15

[El Camexican]

I installed a set of new Boyesen reeds last week, dropped the pilot to a 45 and the main to a 162.

Still seems a little fat at the bottom, but it cleaned up a lot at the top. If I had to guess I would say retarding the timing a couple degrees may be all that is needed. If not them I guess CF reeds will be needed.

The swing-arm is half done and waiting on some other projects to be finished, but by years end I expect to have the swinger installed with a 48T rear and a non-o-ring chain. I need to get the longer brake line ordered as well.

Still debating a set of 4 SNOWS. Any opinions would be appreciated based on this thing being used at the drags only.

TF is only 7 months away, time sure seems to fly.

[barnett468]

.
Hey El, glad to hear you got it running . . I'm not sure how much you know about dirt drag racing, and I am certainly not the foremost authority on it, but I posted some stuff that might be helpful, some of which you probably know but I figured I'd cover the bases anyway just in case.

Also, you might consider starting a separate thread for drag racing titled something like "What is the best tire and suspension setup for Trike Fest Drag Racing" because I think you will get more answers simply because more people will see it.


CHAIN

I would run the RK 520 MXZ4 chain . . It is one of the lightest available and should be good for another hp or two . . It comes in all the colors of the rainbow . . If you don't trust master clips you can use the rivet type.

http://rkexcelamerica.com/products/b...irt-bike-chain


SUSPENSION VS TRACTION VS WHEELIES

A bouncing bike is a bad thing.

Wheelie bars can help but people have won without them.

I would try it with lower suspension to reduce the potential for wheelies but the lower it is the less traction you will have, so you might want to test it with stock height and lowered.

REAR - I would lower it around 2 1/2 to 3 inches from stock and check the fender to tire clearance when bottomed and install a spacer on the shock shaft between the bottoming bumper and the shock if needed . . You can use cheap aluminum to reduce weight and reduce the chance of scratching the shaft and it needs to be almost the same diameter as the shock body . . You can just use a tie down to pull down on the suspension which will obviously make it a bit stiffer which "should" also help . . Try it with the damping settings on max.

If you use the 4 Snow type tire, they will bounce, so you might also try removing the shock and installing a solid bar . . You could even make it adjustable inexpensively by using a swedge tube and heim rod ends . . This will also reduce the bike weight by maybe 6 lbs . . If you do this, just remember to use 1 right hand thread and 1 left hand thread joint.

FRONT - Lower this by the same amount, but if it gets twitchy at high speed, raise it up until it is at the best setting.

If you don't have air caps or do but don't want to mess with air, preload the front springs around 1 1/2" and run 20 wt fork oil.


TIRE PRESSURE

Try it low and try it high . . Any change less than 3 lbs will be hard to notice so I wouldn't bother with 1 lb increments . . This will save you some testing time.


TIRE TYPE

I see you have been doing your homework . . This being said, the winners in 2014 were running Ohtsu Pro Wedge II's . . They work better than the snows in harder packed dirt and are what a lot of the drag guys I know are running but they them backwards . . Unfortunately they are only available used so Ebay is one place to find them . . There is a set on there now.


I'm guessing you checked out the 2014 Trike Fest drag videos but if not, you can see 3 top bikes in the one below and they all have Ohtsu Pro Wedges.

https://www.youtube.com/watch?v=PRSInzPgV_Q


RIM TYPE AND RIM WIDTH

I would consider using the 10" wide .125 Mitchell's with them . . They will have reduce expansion and bounce and increased contact area over using them on 9" wide rims.


IGNITION TIMING

I wouldn't worry about adjusting the timing for better bottom end since you will only be running at top end at the drags and the more rpm the merrier . . As long as your timing is not too far advanced, the more you run, the more power it will have so basically, if it doesn't ping now, retarding it will make it richer and reduce power everywhere including on the bottom . . I would set it until it revs the highest, then retard it 2 degrees so you have a margin of safety . . Basically, if you are running stock timing, it likely does not have enough advance but this depends on the rate your fuel burns also, so you should time it with the fuel you will be using.

I would also get a tach and possibly a detonation sensor . . You can get digital tachs as cheap as $10.00 but of course it is a $10.00 tach.

Tach

http://www.ebay.com/itm/Hour-Meter-T...-/360845036042

Your ignition also may not provide enough advance and if you get a programmable one, you can set it to the optimum level . . PVL might have one but MSD does for sure . . It is $300.00.

https://www.mpsracing.com/instructions/MSD/4217.pdf


REAR AXLE BEARINGS

I would consider some low friction ones . . They are a bit pricey but they will last a long time and are good for a couple hp . . Ceramic bearings are even better but are expensive and not necessary for your app since you aren't running a Honda . . Some places like Applied Tungstenite can coat your bearings . . Check with the places below for info.

http://www.appliedtungstenite.com/html/bearings.html

http://www.microblueracing.com/micro...-bearings.html


COOLANT

This is a long and complicated subject, but in short, one aspect of anti freeze is that it is around 3 times more viscous [thick] than water, so it puts more load on the water pump which in turns eats a little more hp but not a very much . . I would consider running 15 % antifreeze and some water wetter type liquid but a different brand like Purple Ice and the rest distilled or purified water but tap water wont hurt.

I would also run a slightly higher pressure rad cap . . Rocky Mountain ATV has them.
.

[El Camexican]

Oh my, here goes, not sure if the skin on my finger tips is thick enough thou...

.CHAIN

I would run the RK 520 MXZ4 chain . . It is one of the lightest available and should be good for another hp or two . . It comes in all the colors of the rainbow . . If you don't trust master clips you can use the rivet type.

I know you meant to say "free up another hp or two" so I won't tease you about it. Already ordered a KTM non-o-ring orange chain. I'm 99% sure it's made by RK. I bought it for the color, otherwise I would have bought a D.I.D. Saw you comment that they were a "decent" chain the other day. My D.I.D. ERV3 chains go 3,000 miles without needing a single adjustment on steel sprockets. So far I've been selling them for $50 bucks to others when I change my counter sprockets and put a new chain on. If I was concerned about breaking a chain I would buy an EK. They make a 630 that can handle over 1000hp stuck to a slick.

SUSPENSION VS TRACTION VS WHEELIES

A bouncing bike is a bad thing.

Wheelie bars can help but people have won without them.

I would try it with lower suspension to reduce the potential for wheelies but the lower it is the less traction you will have, so you might want to test it with stock height and lowered.

REAR - I would lower it around 2 1/2 to 3 inches from stock and check the fender to tire clearance when bottomed and install a spacer on the shock shaft between the bottoming bumper and the shock if needed . . You can use cheap aluminum to reduce weight and reduce the chance of scratching the shaft and it needs to be almost the same diameter as the shock body . . You can just use a tie down to pull down on the suspension which will obviously make it a bit stiffer which "should" also help . . Try it with the damping settings on max.

If you use the 4 Snow type tire, they will bounce, so you might also try removing the shock and installing a solid bar . . You could even make it adjustable inexpensively by using a swedge tube and heim rod ends . . This will also reduce the bike weight by maybe 6 lbs . . If you do this, just remember to use 1 right hand thread and 1 left hand thread joint.

FRONT - Lower this by the same amount, but if it gets twitchy at high speed, raise it up until it is at the best setting.

If you don't have air caps or do but don't want to mess with air, preload the front springs around 1 1/2" and run 20 wt fork oil.

Wheelie bars are not allowed in the mod class as far as I know. Unfortunately my 4" swing-arm extension is going to raise my rear end and my front forks are dropped about about 1.5" as I have a slight bend in the tubes that I have positioned to straighten out over time (I hope). I was thinking of strapping the rear down 3 or 4 inches if they will allow it. BUT, I am also thinking that having the ass high without a wheelie bar, or 8" over swinger may be an advantage out of the hole as it will allow a little more wheel spin.

The constraints of this class tell me that it's all about the clutch and who can get to third gear first without lifting the front wheel too high. As far as top end stability as it relates to the stance of the chassis I don't think the speeds reaching in this competition will cause it to be an issue. I'm guessing 50 - 60 MPH would be the highest I'd get to. I have a Works rear shock build to my weight and a set of Progressive springs up front and do have air caps. Should be overkill for a drag racer. Hopefully the swing-arm extension won't fudge the rear too much, but if it does I can send the shock back to them with the new specs.

TIRE PRESSURE

Try it low and try it high . . Any change less than 3 lbs will be hard to notice so I wouldn't bother with 1 lb increments . . This will save you some testing time.


TIRE TYPE

I see you have been doing your homework . . This being said, the winners in 2014 were running Ohtsu Pro Wedge II's . . They work better than the snows in harder packed dirt and are what a lot of the drag guys I know are running but they them backwards . . Unfortunately they are only available used so Ebay is one place to find them . . There is a set on there now.


I'm guessing you checked out the 2014 Trike Fest drag videos but if not, you can see 3 top bikes in the one below and they all have Ohtsu Pro Wedges.

https://www.youtube.com/watch?v=PRSInzPgV_Q


RIM TYPE AND RIM WIDTH

I would consider using the 10" wide .125 Mitchell's with them . . They will have reduce expansion and bounce and increased contact area over using them on 9" wide rims.


IGNITION TIMING

I wouldn't worry about adjusting the timing for better bottom end since you will only be running at top end at the drags and the more rpm the merrier . . As long as your timing is not too far advanced, the more you run, the more power it will have so basically, if it doesn't ping now, retarding it will make it richer and reduce power everywhere including on the bottom . . I would set it until it revs the highest, then retard it 2 degrees so you have a margin of safety . . Basically, if you are running stock timing, it likely does not have enough advance but this depends on the rate your fuel burns also, so you should time it with the fuel you will be using.

I would also get a tach and possibly a detonation sensor . . You can get digital tachs as cheap as $10.00 but of course it is a $10.00 tach.

Tach

http://www.ebay.com/itm/Hour-Meter-T...-/360845036042

Your ignition also may not provide enough advance and if you get a programmable one, you can set it to the optimum level . . PVL might have one but MSD does for sure . . It is $300.00.

https://www.mpsracing.com/instructions/MSD/4217.pdf


REAR AXLE BEARINGS

I would consider some low friction ones . . They are a bit pricey but they will last a long time and are good for a couple hp . . Ceramic bearings are even better but are expensive and not necessary for your app since you aren't running a Honda . . Some places like Applied Tungstenite can coat your bearings . . Check with the places below for info.

http://www.appliedtungstenite.com/html/bearings.html

http://www.microblueracing.com/micro...-bearings.html


COOLANT

This is a long and complicated subject, but in short, one aspect of anti freeze is that it is around 3 times more viscous [thick] than water, so it puts more load on the water pump which in turns eats a little more hp but not a very much . . I would consider running 15 % antifreeze and some water wetter type liquid but a different brand like Purple Ice and the rest distilled or purified water but tap water wont hurt.

I would also run a slightly higher pressure rad cap . . Rocky Mountain ATV has them.
.

Tire pressure will be have to be set for each type of condition. I've been trying to think of a place here where I can test it properly. Most flat terrain here is hard packed like a gravel road.

I have a $30 tach I plan to hook up. I can attest to the $10 eBay ones not working and not covered by warrantee.

Timing changes will have to be tuned to fuel as you say. I still haven't found any one that wants to sell me some C12 down here and I can't ship it to our warehouse in the States because OSHA recently raped us and all fuels are stored outside.


Rims are 9 or 10" ITC, I'm not planning to change them.

Stock rad cap stays, I'd rather piss it out the overflow tube than the head gasket.

Coolant is 75% water

Ceramic bearings, adjustable ignition curves and detonation sensors are all way out of the budget I'm willing to give this thing. If winning at all cost was the issue I would be posting about fitting a single front wheel to a nitro sand rail. Not happening! Would I like to win the mod class? Hell yea! Will I? I doubt it, I'm probably going to get smoked by someone on a bone stock wore out Tecate, but it would be nice to be the quickest Tri-Z with under 250cc's pulling it.

[barnett468]

.
Ok, then as your primary question regarding the tires goes, the 4 SNOW's certainly aren't a "bad" choice at all then, and I would get 20x10x9's if I used them, but here's a bit more info.

In 2012, one of the top bikes used the Duro HF245 20x11x10 in the photo below.

The Ohtsu Pro Wedge hook up a bit better than the 4 Snows on hard packed dirt like the Trike Fest track has.

Lots of drag racers also use the Ohtsu MR 501's and Dunlop KT335's on dirt like Trike Fest has.

My point being that there are a few different types of tires that will be highly competitive in case you wanted to tun something other than the 4 SNOW's there.

Pro wedge II ........ 11.8 .. 22x11x8 . . Discontinued
MR 501 ............... 13.2 .. 20x10x9 . . Last used on 2012 400xX & 400EX so may still be available . . p/n 42711-HN1-004?
Dunlop KT335 ..... 14.4 ... 2-x10x9 . . Discontinued but some shops may still have
4 SNOW approx ... 15.0 .. 22x10x8 . . Available
Duro HF245 ............. ? .. 20x11x10 . They also make 20x11x9 . . Available.
Duro Sand and Snow . . This is nearly identical to the 4 Snow's tread, but I don't know anything about it

These Ohtsu MR 501's are purportedly new and this may be the last new pair one will ever see, because if they aren't already discontinued, they most likely will be soon . . There may also be a date of mfg on tire . . $190.00 plus shipping.

http://www.ebay.com/itm/OHTSU-20x10X...-/291498594381

Used Ohtsu Pro Edge II's . . These look very good but ask about sidewall cracking . . This ad just ended and they did not sell, but I have an Ebay account and can contact the seller if you want . .$100.00 with aluminum Honda rims.

http://www.ebay.com/itm/Hondaline-Oh...p2047675.l2557


OHTSU MR 501




DUNLOP KT335

......


DURO HF245

[onformula1]

I installed a set of new Boyesen reeds last week, dropped the pilot to a 45 and the main to a 162.

Still seems a little fat at the bottom, but it cleaned up a lot at the top. If I had to guess I would say retarding the timing a couple degrees may be all that is needed. If not them I guess CF reeds will be needed.

The swing-arm is half done and waiting on some other projects to be finished, but by years end I expect to have the swinger installed with a 48T rear and a non-o-ring chain. I need to get the longer brake line ordered as well.

Still debating a set of 4 SNOWS. Any opinions would be appreciated based on this thing being used at the drags only.

TF is only 7 months away, time sure seems to fly.

Since the Pro Wedges are hard to come by and most after 30 years are cracked, I would run the best replacement the 4 Snow

http://www.maxxis.com/catalog/tire-363-4-snow

They are light, 2 ply, have killer traction and are 22" tall which is what you want for the drags.

The longer swing arm will need a stiffer spring due to leverage and chain torque. (Contact me, I will help you out)

You may consider running AVgas in Mexico until you can buy fuel in the USA, I have a few sand drag racing friends in Mexico that run it with fantastic results. Because of the nature of a airplane that fuel in equal in quality to US standards. Look for 100LL I have been told it is called "Azul" in Mexico. (Check with the airport to be sure)

Don't worry about the chain there have been dyno tests performed where the best non o-ring chain vs. the worst o-ring chain was less than 1/5 of 1 horsepower.

On a 2 stroke-
Retarded timing= more upper mid, top end & over rev

Advanced timing= more low end and mid

As for jetting- don't forget what your launch RPM will be.