4 stroke questions * PWC eng. transplant

[Tori89k5]

Hi guys, first off i'll introduce myself. Tori here, long time boater, but am currently into vintage personal watercraft. Mainly, i am into the old Wetbikes.

The Wetbikes used a DT50 and DT60. As you all know, these are 2-strokes.

I'm considering taking on a project to convert one to use a 4 stroke engine.

I have several questions i'd like to ask before i get too serious about this project.

I am considering at the minimum, a DF60 but since im going thru all this trouble, and extra 10hp wouldn't hurt, so maybe a DF70

The first few things i have to figure out is the weight of either of these powerheads. Does anyone know the weight of just the powerhead on either of these engines ? The DT50/60 weighs in at almost 100# So as long as we are close to that i should be okay in the weight dept.

Next up is RPM. Since the Wetbikes run impellers, the correct RPM is a must. We are getting about 5500-5600 rpm out of the 2 strokes. I need to be pretty close to this or else the swap wont be worth doing. I can play with the impeller some, but not too much. Maintaining a competitive speed with the 2 strokes is key.

Height of the DF60/70 is also a factor. Anyone care to measure the powerhead section of their motor for me ? I've got to be able to fit this in the hull, otherwise ..... well, you know.

I'll stop at these 3 issues for now, and see if this is even possible.

Thanks in advance,
TORI

[Tori89k5]

Nothing ? anybody....... ?

[mphelle8vld]

Always enjoy a good project. The DT50/60 is a 2 cylinder, the DF60/70 is a 4 cylinder inline so I think it would be too tall and heavy for your application. My experience is in outboard jets and I have found that 2 strokes jump up on plane quicker than the 4, they just rev quicker.

[Tori89k5]

Thanks for the reply. I figure the 4 stroke will be longer, and heavier, but by how much? That's what i'm trying to figure out. I have some wiggle room on height, and weight is subjective to how heavy the rider is. I'm light, so i have lots of room to go up in weight.

Any chance you have either of the two motors im inquiring about DF50/60 and could get me a measurement on height ?

And what RPM do the 4 strokes run to ?

I'm not doing this swap for the performance gain, but more on the ecology side.

[mphelle8vld]

Strictly a polluting two-stroker, I sleep at night knowing that I only use my rig to catch dinner.

Maybe find someone in your area selling a DF70 and go take measurements.

[Tori89k5]

Being from California, i know my 2 stroke days are limited. They've already got a ban in place for Lake Mojave starting in 2012. Hoping to have an alternative when my time comes.

On the bright side, i did just speak to a guy selling a DF60/70 block on ebay. he was a great help. Sounds like the Honda and Yamaha 4 stroke are the lightest outboards.

So, i'll start looking at those engines too.