HAve a feeling

[86trizinger]

Well i got my son a 2009 DRX 90 H20 for Christmas.. I havent even got it up and running yet. After talking to a few people I think I should have went for the 70cc instead. I didnt realize the age span for the 90cc ; 8-15 . It is first year racing so I need to know what to do . SHould I just buy a DRX70 engine and through it in there. I have a good Eton 70 engine but its not watercooled and I really dont know if that would be allowed. So I dont know if I need to convert that over to a H20 engine or not.

Any input on this would be great. He jsut want to go out and have some fun. A few Hairscrambles and maybe a MX or 2 to start with this year.

[JIM GRACE]

how old is your rider?? and you can switch to drr 70 jug and piston for less then you think..

[WISH1965]

86,

This the same dilema I have, got a DRR 90 now, will still race the 90cc, but want to also race 70cc and very few used 70's out there. So if i bought a 90cc, the thought is to get a 70 motor. I didn't you could go backwards, IOW's 90 to a 70 can't be done or at very cost prohitive, but to go from a 50 to a 70 is not a big deal? At least this is the feedback I'm getting?? Any advice?

[86trizinger]

From what I was told the crank is different in the 90cc , its the same in the 50 and 70cc which makes justa piston change easy. I dont know of any way to make the 90 a 70 without a crank change. My son has a TRX 90 which would run in some of the 70cc classes but I am sure he is going to prefer the DRR since it will be his new one.

I already have a 70cc eton I could swap the engines around but the problem is the DRR is watercooled and the eton is aircooled. I am not sure how the rules are.

[hotquads1]

Originally posted by 86trizinger
From what I was told the crank is different in the 90cc , its the same in the 50 and 70cc which makes justa piston change easy. I dont know of any way to make the 90 a 70 without a crank change. My son has a TRX 90 which would run in some of the 70cc classes but I am sure he is going to prefer the DRR since it will be his new one.

I already have a 70cc eton I could swap the engines around but the problem is the DRR is watercooled and the eton is aircooled. I am not sure how the rules are.
.
putting the 70 eton motor in should be keeping with the spirit of the rules although it is another brand case, it is still a pruduction case and interchangable with the DRR case. Drr comes l/c or air cooled so that should not be an issue. IMO . but if you intend to race ATVA events I would get a confirmation from them on this .
marc

[quadscrib]

From what I understand (which meens little) the cylinder studs on the 90's are farther apart than on a 50/70 motor making 90 to 50/70 cylinder changes realisticly impossible.

[hotquads1]

the studs are spaced the same , that is not a problem.

[86trizinger]

well i got a stock DRR 50 bottom end. So i need to find a stock 70cc top end to put on the engine. If anyone has anything please let me know.

[quadscrib]

Wow I really thought Id read they were different. So is it just piston/cylinder differing between the 50's-70's-90's?

The 50's have a 39.2mm crank and littler splines and the 90's have a 42 mm crank larger splines as the 39.2 is for 50 and 70's everything else should be the same i hope this helps you out. you can put a 47.6 mm top end on and be a 70 i believe. yes just put the 70 top end on a 50 and have a 70.

[86trizinger]

To make my 90 I would need a 46mm piston ... With a 47.6mm piston it will be a 75cc which is too large for its class.. Wher can find if anyone makes a 46 mm piston at? I can only find the 47.6mm pistons.

[dericsdad]

Take your eton 70 and install an LC 70 top end. Marc should be able to hook you up with that. he could also tell you what to do with the clutches etc. to make it run with the DRR's.

The 90's crankcase has a larger volume, so if you could get the right cylinder/piston combo to put on your crank, it will be a slug.

Otherwise, If you want to sell your 70cc Eton motor, I'd be interested.

Dan

[86trizinger]

Thats what I was planning on doing I think now.. I have the Eton 70 motor and a KASEA 50 motor. So I could do some swapiing around and hae the spare 90 engine for next season. Looks like the most cost effective. The 70 motor I have already has clutch mods done to it.. I am just not sure what until I get it apart.

[hotquads1]

if you have a DRR 50 engine , it will be easy to convert to a 70 , I have everything in stock (cylinder, head , piston) . As said derics dad said building a 70 on a 90case is not the best way to go, building a 90 on a 70 case requires machining and crank change but can work well.
marc

[86trizinger]

What would it take to use the KASEA 50 bottom end and cover it over to the DRR top end and water pump. Will all of the parts interchange.

I am just trying to figure out exactly what I want. He gets the ATV for Christmas almost stock. I just added nerf bars and handle bars to start. A couple months for him to get used to the bike. Then I have to upgrade the front shocks and engine before march though but will be limited to stock parts.

[hotquads1]

I am assuming your Kasea 50 has a 39.2 mm crank in it , so the conversion would be same as a drr 50 would be . you will need
70 cyl
head
piston
gaskets and seals
water pump and cover ( can be reused from the 90 engine)
drive studs for flywheel (3) (can reused from the 90 engine)
marc