DR 790 big bore kit from precycle

[R Clark]

Anyone had this done ? Im having my tired ol girl fitted with this plus a new cam and pumper carb. Not cheap i know but hell it is what it is.
Parts arrive shortly boyz are chomping at the bit ready to breathe new life into her. They seem more excited than me. So who's had it done
or is thinking about it . Just curious

[Night Falcon]

no comment but keen to hear how it turns out :corn:

[JATZ]

Flick phreaky Phil a p.m. He had one on his 650. I think he had some teething problems when it was first installed.
Good luck with it though

[badblackbuell]

I'll be keeping an eye on your progress. I have a Dr in pieces currently and the barrel is worn badly. Only 27km on it but gearbox looks naff too. I have a je forged piston to go in but looks like a big bore might be better. Will you be doing the big valve head?

[Muzz67]

I'll be keeping an eye on your progress. I have a Dr in pieces currently and the barrel is worn badly. Only 27km on it but gearbox looks naff too. I have a je forged piston to go in but looks like a big bore might be better. Will you be doing the big valve head?
Box knackered at 27?!
how longs a new one gonna last with 790cc pounding on it?

[R Clark]

Flick phreaky Phil a p.m. He had one on his 650. I think he had some teething problems when it was first installed.
Good luck with it though

Cheers man

[R Clark]

I'll be keeping an eye on your progress. I have a Dr in pieces currently and the barrel is worn badly. Only 27km on it but gearbox looks naff too. I have a je forged piston to go in but looks like a big bore might be better. Will you be doing the big valve head?

Gonna leave the head alone for now just shove these other bits in . yeah i"ll post more as we go. Cheers

[R650R]

no comment but keen to hear how it turns out :corn:

Me too :) :) :) :)

[badblackbuell]

Box knackered at 27?!
how longs a new one gonna last with 790cc pounding on it?

Good call. Mechanic reckons switching to 20w50 should see longer gear life. Been running 10w40 semi up til now.

[MarkH]

Mechanic reckons switching to 20w50 should see longer gear life. Been running 10w40 semi up til now.

I'd give that a 'maybe'.
Thicker oil has a greater shear strength but thinner oil flows to where it is needed quicker.

[GrayWolf]

Guess if you google the DR BIG threads on the DR owner sites {I think there's a few} you'll get an idea of ownership issues etc
The DR 750/800's didnt seem to stay in production for long, or in any great numbers

[Phreaky Phil]

I did the 790 Kit for our Trans America trail bike. In order to get it done right I sent a standard barrel to Procycle and they got their Sleeve company to fit the 790 liner. They must have given it to the apprentice boy to do as for some unknown reason they machine about 1.5 mm off the bottom of the barrel. When I got an engine guy to put it in here he noticed it was different and did some measurements and added more base gaskets to compensate but it was right and we didn't have enough piston to head clearance and it would just touch when cold and would knock.i did a couple of thousand km but knew something wasn't right and pulled it apart. Procycle replaced the whole thing but we were to close to our TAT trip and I never fitted it. Sold it to a guy in Aussie in the end. It ran like a freight train though. Huge torque but probably no more top end than my 650 with the Keihin carb and exhaust.
If I was spending that much money I would want it on a fully rebuilt or low km engine.
If I did another one I don't think I would do another big bore, but aim to keep its torque but make more top end power.
They can be made to go really well with the stock carb and a change in exhaust.
If I remember the name right, was it Gavin with a blue big tanked one had his dialled in really well.?
I was fast enough (2 up ) to make a certain KTM 690 rider think something was wrong with his bike :laugh:

[Scubbo]

wouldnt you be better off doing the head/big valve instead with a good exhaust and pumper carb would make it sing

[R650R]

Bump.... update????