Jump to content
Sign in to follow this  

700cc Big Bore DR 650

Recommended Posts

I came from a sportbike background & when I got my 2008 DR 650se, I thought, "this thing is a BLAST to ride but I just have to have more power"!

so it didn't take long before the mods began (only has 1300 miles on it now).

I started with a mix of parts, some from Jeff @ procycle & some from Jesse @ kientech, with a few other parts here and there.

It went with a TM40 carb, FMF Q2 muffler & oversized header, modified airbox & filter setup, web cam & now finally a 700cc big bore & the porting to give it the additional flow it requires to make the most of the increased displacement.

I've also ordered a custom head gasket from Cometic to reduce the squish height (& increase compression) & I will be getting the head milled to increase compression & a 3 angle valve job to help with the flow & ensure that the valves seal in all of the additional compression.

here are some pics along the way.

P.S. I also have a video on youtube about porting:

BigBore056.jpg

BigBore076.jpg

BigBore083.jpg

BigBore086-1.jpg

BigBore096.jpg

BigBore097-1.jpg

BigBore094.jpg

BigBore105.jpg

BigBore107.jpg

BigBore111.jpg

Share this post


Link to post
Share on other sites

sorry for the dust in the ports, the camera sees better than I do & it shows ALL of the flaws!

the intake ports are not finished as well as the exhaust because I'm going to make them a little coarser on purpose to promote atomization. I just polish them a little so that I can easier see all of the problem areas.

BigBore117.jpg

BigBore118.jpg

BigBore121.jpg

BigBore122.jpg

BigBore013.jpg

DR650071.jpg

DR650070.jpg

DR650094.jpg

DR650100.jpg

DR650102.jpg

  • Like 1

Share this post


Link to post
Share on other sites

Lots of nice goodies you got there! Love the porting job, I am too scared to do those myself nowadays. On my last attempt with a small block V8 head I managed to break into a water jacket.:eek:

Is the cam a custom grind for your application? You have to put that thing on a dyno when you are done, will be very interesting to find out how much power it makes. The most I remember reading about was 48 RWHP on a Dynojet, similar setup to yours except stock displacement.

Good luck with the engine build!:worthy:

Share this post


Link to post
Share on other sites

hit a water jacket! OOPS! not likely to happen on this motor LOL.

where did you hear about the 48HP DR? do you have a link or a title I can search for (if on this forum)?

Share this post


Link to post
Share on other sites
hit a water jacket! OOPS! not likely to happen on this motor LOL.

where did you hear about the 48HP DR? do you have a link or a title I can search for (if on this forum)?

Yeah, it kind of sucked. Luckily I was able able to get it welded and it cleaned up pretty nicely. But I learned my lesson and now let the pros handle the things that require fine motor skills.:worthy:

This is the 48HP DR I was talking about:

DSC_0004.jpg

Here is a list of the mods (off his website):

Custom stainless exhaust

Custom Pro circuit T-4 silencer

15% harder clutchsprings

Proffessionally ported cylinderhead

New bearings in the engine(Complete list)

JE Pistons highcomp piston 10,5:1

Webcam 223 regrinded camshaft

Mikuni TM40 flatslide carburetta

K&N airfilter

You can find out more on his website:

http://www.huttenatt.com/?lang=eng&page=projekt&pjk=dr650sm

There was also a thread on Thumpertalk but I can't find it right now.

Share this post


Link to post
Share on other sites

thank you!

& I forgot to answer, my cam is the same grind as his, it's just the "off the shelf"

web cam grind for DR650's.

Share this post


Link to post
Share on other sites

Can't wait to here more about the results.. I have the JE High Comp Piston and Web cam on the way.. Just curious are you going to offer porting services for DR heads?

thanks,

Gary

Share this post


Link to post
Share on other sites
Beautiful work on the porting. :worthy:

Any numbers on the compression ratio?

I haven't had it milled yet but I'm shooting for 10.5:1

Share this post


Link to post
Share on other sites
Can't wait to here more about the results.. I have the JE High Comp Piston and Web cam on the way.. Just curious are you going to offer porting services for DR heads?

thanks,

Gary

I look forward to hearing about your adventures as well, feel free to post your progress here.

I've already been doing head porting on sportbikes, I'd not be opposed to doing DR's also.

Share this post


Link to post
Share on other sites

I'm just curious how much improvement the DR head has in it..I'll be looking forward to hear your thoughts once yours is on the road.

Gary

Share this post


Link to post
Share on other sites
I'm just curious how much improvement the DR head has in it..I'll be looking forward to hear your thoughts once yours is on the road.

Gary

it's hard to gauge power # wise since we're talking about a motor that only puts out 35 HP stock.

it's like, even if I get a 10% gain, that's only 3.5 HP.

it's been my experience that it's not just the peak #'s but the area "under the curve" that's really what you're looking for. I think it'll make a dramatic difference in the way it runs.

one of the problems is being able to mill enough off of the head to get the compression I'm looking for. the limit is going to be the intake valve seat, I may be cutting into some of it if I go as far as I want.

Share this post


Link to post
Share on other sites
one of the problems is being able to mill enough off of the head to get the compression I'm looking for. the limit is going to be the intake valve seat, I may be cutting into some of it if I go as far as I want.

I have found it is often easier to mill the top of the cylinder rather than milling the head.

Share this post


Link to post
Share on other sites

a few more pics.

now I have the intake tract "roughed up" to promote atomization, notice I've left the bowls semi polished.

the other pic shows that I've matched the intake boot to the intake tract.BigBore131.jpg

BigBore137.jpg

BigBore127.jpg

Share this post


Link to post
Share on other sites
Any tips on where to get a spare DR head besides dealer?

I just bought one off of ebay for about 55.00

Share this post


Link to post
Share on other sites
I have found it is often easier to mill the top of the cylinder rather than milling the head.

that is another option but that will also reduce my piston to head clearance.

Share this post


Link to post
Share on other sites
that is another option but that will also reduce my piston to head clearance.

Just curious, what's your target compression ratio?

Share this post


Link to post
Share on other sites
Just curious, what's your target compression ratio?

for now I'm looking for 10.5.

I'll see how that goes before I decide if I need/want to go higher.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...