so me and my dad have 2 dtr frames so the plan is to build one original to sell on for the road and to fund the other project. both 2000-2003
So on to the good Stuff. the plan is to build something different and still roadworthy.
my question is how to make the dt hit a 90mph or maybe possibly the 100mph.
so far ....
standard bottom end.
standard top end. 3MB Head and barrel << the idea here is to keep factory engine with a bit off barrel porting >>
one of Romero's underslung exhausts
32mm carb
uprated clutch plates
the least unrestricted CDI << advice on this please model numbers etc..>>
Gearing not to sure here << advice and Reviews on different sprocket settings >> my road DT has a 17-57 and will hit 75 on clock so realistically 70mph
remove as much weight as possible but keeping the PV functional. will be run off a smaller 12v battery
i will add for what we are trying to achieve the Engine has to remain visibly stock.. so unfortunately no athena 170 kits or wr200 barrels or 230 barrels :(
Best thing for the money is a Zeeltronic ignition system. It's fully programmable and makes a MASSIVE difference to the mid range and over rev. Can remove the rev limiter and get it spun up to 14K. This will make a big difference to your top end and since you're racing a rebuild won't be a problem.
Get the barrel 'aggressively' ported by Mick Abbey. Make sure you get the Head done as well.
Get the bottom end polished and ported. Oil dwellings enlarged.
Get a decent flat slide carb, go bigger I'd suggest VHSB carb and have that gas flowed.
Go RAM air filter and remove as much weight as possible.
Go plastic tank. No Panels, no battery.
Swap the gearbox out for a TZR125R Belgarda gearbox (It has to be a belgarda gearbox I have one for sale if needs be) this will dramatically change the gearing allowing you to achieve your top speed.
I'd remove the powervalve and motor, this will allow for greater porting and is not necessary for racing. Once your RPMS are higher than 6K the valve stays open so there is no need for a operational valve.
Make your own custom loom, you will be surprised how much the copper weighs.
You only need a loon from genny to CDI. So only a couple wires necessary.
Remove the rear subframe.
Can use a DT200WR alloy swing arm and DT230 Lanza Alloy wheels. (or other aluminium wheels).
Saving weight where possible is key to fast launch and max speed.
I mean you will probably only get 20 bhp out of this engine, any more will require ridiculous amounts of money.
unfortunately the Club only allows you to use the Whole engine that came with the bike Factory so no bottom end change outs. :(
i believe CDIs can be changed and most of the electrics and weight can be shaved off wherever necessary as long as you have a satisfactory seat and tank.
regarding wheels and forks, are the supermoto wheels heavier??
and i would assume USD forks are also heavier?
barrel will be ported by BoB Farnham Racing and wave racing developments.
i agree the LOOM will be minimal but we will make our own rather than chopping up a decent loom!! its highly annoying when people do that.
So that there is my rebuilt, forged TZR125R Belgarda engine. Notice anything? It's identical to the DTR DTRE engine and no one would know it's actually a rare TZR engine with a TZR gearbox.
The build thread is on here if you want to see how close it is.
As for sprocket ratio, you will have to remember that if you decide to use a longer gear ratio, you will need smaller front and bigger rear sprockets. It won't be as simple as saying I'll have this, it'll be trial and error whatever you choose.
At least if you use a belgarda engine it comes from this bike,
So you know you're going to get more top end.
-- Edited by Calum122 on Wednesday 17th of June 2015 10:06:14 AM
very interesting and tempting the problem being is the lack of cash (reason why where building the second bike original) and it's only just been sprayed.
i'll see what my dad thinks we have in the money pot :) and ill get back to you but i'm interested!
we have 2 goals to achieve
1. quickest standing 1/4 mile
2. top speed in 1 mile
obviously there will be 2 sprocket setups needed. short and long gear ratios.
how many horses do you think you would need to break the 100mph barrier i know the RS 125 can do it but it's got fairings and and a better tuned engine.i Hate the rs owners favorite saying "full power 33bhp" lol
just double checked with the guys it must have a working PV! no issue just minimise the weight and maybe give a better start off the line.
Again it won't be power necessarily, aero dynamics, weight and sprocket setup will be key to reaching 100 mph. But this will not feel very safe at this speeds.
I'd suggest using bigger dog bones to lower the ride as much as possible to achieve better stability under speed and lower centre of gravity.
TDR wheels will be a good shout and check the wheel section as Seiki posted what is required, I believe. Definitely scrim has so just have a search on here!
Best thing for the money is a Zeeltronic ignition system. It's fully programmable and makes a MASSIVE difference to the mid range and over rev. Can remove the rev limiter and get it spun up to 14K. This will make a big difference to your top end and since you're racing a rebuild won't be a problem. --Definitly agree with this
Get the barrel 'aggressively' ported by Mick Abbey. Make sure you get the Head done as well. - Doesnt have to be mick abbey :P Get the bottom end polished and ported. Oil dwellings enlarged. Get a decent flat slide carb, go bigger I'd suggest VHSB carb and have that gas flowed. - Don't know about the vhsB but the VHSA 32mm which goes on the belgarda. Whats the B model cal? Go RAM air filter and remove as much weight as possible. -+1 on the ram air filter. get rid of all the airbox etc. Go plastic tank. No Panels, no battery. -You can get one of the battery bypass bits on ebay for about 8 quid.
Swap the gearbox out for a TZR125R Belgarda gearbox (It has to be a belgarda gearbox I have one for sale if needs be) this will dramatically change the gearing allowing you to achieve your top speed. +1 on this too. This shouldn't affect your rules. Its a gearbox for that engine.
I'd remove the powervalve and motor, this will allow for greater porting and is not necessary for racing. Once your RPMS are higher than 6K the valve stays open so there is no need for a operational valve. - This im not sure on. it was the YPVS that won Yamaha loads of championships when they first started using it. I'd just adjust it using the zeel and keep it operating.
Make your own custom loom, you will be surprised how much the copper weighs. -Sounds sensible
You only need a loon from genny to CDI. So only a couple wires necessary.
Remove the rear subframe. - What you gonna sit on? Maybe remove some lugs but getting rid of the lot seems exessive.
Can use a DT200WR alloy swing arm and DT230 Lanza Alloy wheels. (or other aluminium wheels). +1
Saving weight where possible is key to fast launch and max speed. +1
I mean you will probably only get 20 bhp out of this engine, any more will require ridiculous amounts of money. - na im sure you'll be getting more than 20 out of race tuned 125
If I think of something else I'll let you know.
Theres my 2 cents worth. Keep us posted this sounds interesitng.
will get some pictures up and a project thread going when it all starts falling together, atm all i would have to show you is a newly sprayed orange frame with some gunmetal gray yokes and swingarm lol, with parts of a Loom (going custom made as suggested).
Keeping the Frame complete we couldn't bring ourselves to butcher a perfect frame :(
A question on the battery BYpassing units, aren't they just essentially a capacitor ?
Power Valve is staying and are going with a zeeltronic,
we just had some pristine TDR wheels shipped over from germany :) as far as i know are a straight swap apart from a caliper mount on the front. not sure on weight will put them on the scales :)
Fairings and fenders are gone!
Should we Keep the YEIS or bin it ?
any ideas for a Tank obviously only has to hold a litre or 2.
Question on Barrels are the nickel/chrome barrels worth it ? any major advantage i already know the disadvantages :) good old Kx 125,
also remember this is also going to be day time MOT'd so its got to stay roadworthy :)
