GT750 reed intake idea's

Suzukidave · Post by **Suzukidave** » Thu Nov 19, 2009 8:45 am

I know its hard to tell from the picture but the CR250 reeds " look " much like the Arctic Cat 6 petal reeds http://cgi.ebay.com/ebaymotors/1986-hon ... ccessories

Buffalo-guy · Post by **Buffalo-guy** » Thu Nov 19, 2009 10:27 am

I know a good deal when I see one. I suspect the only requirement would be relative ease of locating sufficient reed cages. Either way, count me in if this is a go. Beautiful workmanship, BTW. The old brain gears are grinding bigtime at the thought of the potential. I look forward to future postings on this subject. Cheers.
Fred

durgam · Post by **durgam** » Thu Nov 19, 2009 10:53 am

Im just thinking in terms of airflow and commonality

Suzukidave · Post by **Suzukidave** » Thu Nov 19, 2009 10:53 am

Yeah Fred , reeds would be the next big cost besides the cylinder machining as that was the reason i first went with the AC reeds is that most on ebay came in sets of 3 and i picked up for the 600 and 900 just to see what the difference was . Nothing apparent different but the petal guards on the 900 were spread a bit wider i guess for more flow but the petal material may have also been different but without a flow bench i dont know . I ended up getting a set of V- Force reeds for the 600 AC as they claim to have the best all round low and hi RPM flow but the V-Force reeds arnt cheap for the set of 3

.. Dave

Post by **Suzsmokeyallan** » Thu Nov 19, 2009 10:57 am

Dave id like to say use the AC reeds and have a bunch of the reed boxes made up to those dimentions. The critical thing here is to make the box with the correct angle and flanges on both ends so it allows for bolting up to a plate welded to the cylinder side.

durgam · Post by **durgam** » Thu Nov 19, 2009 10:58 am

I could maybe do 2 styles. 1 for the spigot mounts and 1 just for a custom head.

Suzukidave · Post by **Suzukidave** » Thu Nov 19, 2009 11:03 am

For the reeds to work best it really is needed for the intake side of the block to be machined down to the height of the stud passages in the block to get the reeds in as close to the pistons as possible .

durgam · Post by **durgam** » Thu Nov 19, 2009 11:06 am

Ok. easy enough.

water cooled · Post by **water cooled** » Thu Nov 19, 2009 1:19 pm

My reeds are 1995 Artic Cat ZRT 800's. Id be willing to send them out immediately with a check for a prototype set.

I have a 1974 block that has already been milled with the intake bridge removed so it might be the simplest and easiest to prototype. We can work out how much the block needs to be milled down for these reeds.

I'll be dyno-testing again in April and could make the information available to everyone on the board.

water cooled · Post by **water cooled** » Thu Nov 19, 2009 1:36 pm

Here is an image of a completed GT750 reed race bike for reference.

durgam · Post by **durgam** » Thu Nov 19, 2009 1:42 pm

Im assuming you want them to mount to the tapped holes?

tz375 · Post by **tz375** » Thu Nov 19, 2009 2:05 pm

Kevin,
That's a neat conversion - UK or local?

You might want to try a different block than that for reeds. It needs to be machined flat down to the stud sleeves (same as the lower flange).

Durgam - yes, that is the idea we are floating here.

If you look at the picture Dave posted of a machined box, imagine a completely flat front face of say 10mm thick with a hole that matches the port and flared on the carb side of that flange. That would save several steps in the process and would avoid much of the welding. The reeds will be further away from the piston than perfect, but it's a good compromise.

The box should be shaped better behind the flange to reduce the volume there and should follow the shape of an open reed or the reed stop - say 2-3mm clearance.

As for the angle, street motors need a slight tilt versus stock 5-10 degrees, and racers can use a lot more for a straight shot at the bottom end - 15- 20 degrees.

durgam · Post by **durgam** » Thu Nov 19, 2009 2:23 pm

So I could use my head as a reference for mounting. We just nee dto figure a profile/size for the reed-to-head connection. The holes on water cooled's post looked pretty far apart.

water cooled · Post by **water cooled** » Thu Nov 19, 2009 2:33 pm

The aluminum plate is just an adapter to mount 38mm VM's and the rubber boots. I think those are the holes you are referring to. The aluminum plate would have to go and the block milled even further to get the reeds as close to the piston as possible.

Richard, the reeded GT image is from the U.K. and I believe fits the same reeds that I have. It shows how radical the intake porting can get on a race motor.

Kevin

Post by **Suzsmokeyallan** » Thu Nov 19, 2009 2:43 pm

I was thinking along the lines of milling off all the intake side section of the cylinder as necessary and welding in the plate right across for the reed boxes to bolt onto. With the plate so close to the intake port it will be quite easy to finish dressing the port sides as necessary etc.
Naturally the angle of the boxes flanges are critical so the right carb float bowl clears the clutch hump yet still getting them in as close as possible at the correct angle.
A diagram for side profile angulation and reach is needed for a reed box.

GT750 reed intake idea's

GT750 Race Engine