GT250 Cafe - Build Experiment

Tom Garcia · Post by **Tom Garcia** » Sun Dec 06, 2009 7:09 am

Here's the stock rubbing...

tz375 · Post by **tz375** » Sun Dec 06, 2009 9:44 am

Now that is a most unusual port arrangement. I was hoping that was not what we were going to see. What direction were the two auxiliary/boost ports pointing? Straight forwards and upwards or did they try to point them across the bore?

Tom Garcia · Post by **Tom Garcia** » Sun Dec 06, 2009 10:03 am

tz375 wrote:Now that is a most unusual port arrangement. I was hoping that was not what we were going to see. What direction were the two auxiliary/boost ports pointing? Straight forwards and upwards or did they try to point them across the bore?

Flat tops....frontside just behind center bore...rearside about directly towards each other...

Tom Garcia · Post by **Tom Garcia** » Sun Dec 06, 2009 10:06 am

Vapor and headlight mounted... Fabbed up the aluminum mounting brackets...stock rubber bushings...

two-stroke-brit · Post by **two-stroke-brit** » Sun Dec 06, 2009 10:38 am

hey that trail tech speedo looks neat, how much are they.
cheers mark

Tom Garcia · Post by **Tom Garcia** » Sun Dec 06, 2009 10:40 am

two-stroke-brit wrote:hey that trail tech speedo looks neat, how much are they.
cheers mark

I think this one was about $100 off eBay... I had it on my H2 but it was REALLY erratic... Since the GT has a battery and someone conventional electronic ignition, I am hoping it will be stable...

Tom Garcia · Post by **Tom Garcia** » Sun Dec 06, 2009 2:37 pm

MORE...

Started matching the jugs to the cases... Roughed in the ducts up to the intake from the case....

OOPS! DOH!!! Case gets pretty thin in spots...lower right dark spot... TIG TIME!!!

Quite a bit of difference from the stock holes....

Tom Garcia · Post by **Tom Garcia** » Sun Dec 06, 2009 7:00 pm

tz375 wrote:Now that is a most unusual port arrangement. I was hoping that was not what we were going to see. What direction were the two auxiliary/boost ports pointing? Straight forwards and upwards or did they try to point them across the bore?

Sorry...screwed this up... My previous answer was about the side transfers.. The stock boost ports above the intake point forward and about 45-50 degrees up like "real" ones....

Sorry! Tom

tz375 · Post by **tz375** » Sun Dec 06, 2009 7:24 pm

That makes more sense, but how did they know to do that back in the day?

Those are really big holes. Might want to stop soon. Devcon F or JB weld to fine tune the ports. At the forward face of the reed blocks we want a smooth transition from the reed cages into the barrel and from that flange into the crankcase and combustion chamber.

Total area of the boost ports should probably be around half or preferably less of the main transfers to make sure that most of the gas goes through the main ports. Too much flow from the back will short circuit and trapping efficiency will drop.

How wide are the ports BTW?

Tom Garcia · Post by **Tom Garcia** » Sun Dec 13, 2009 11:18 am

Doh! The used Lectrons arrived.... This should get interesting....

Was planning on moving ports this weekend but had a change of heart... Since Cometic is only about an hour and a half away from the house I'm checking on getting some base spacers made... Might be a better way than trying to move the all the ports up 2-3mm... I can always turn down the top of the jugs....

Tom Garcia · Post by **Tom Garcia** » Tue Dec 22, 2009 4:58 pm

Went over to use the mill today to cut new reed box flanges...and trim a few items...

Seems my buddy has some good barbecues planned... Had a couple sides of beef aging in the tool barn...

Hopefully will have the boxes assembled and attached to the jugs tomorrow!!!

rngdng · Post by **rngdng** » Tue Dec 22, 2009 7:27 pm

I dunno Tom, those are some really big, proposed holes. Size doesn't matter....

Lane

Tom Garcia · Post by **Tom Garcia** » Wed Dec 23, 2009 5:00 pm

rngdng wrote:I dunno Tom, those are some really big, proposed holes. Size doesn't matter....

Lane

And these are the smaller reeds that I wound up using rather that the larger ones pictured above...hence the new boxes.... Need a little more blending...a little epoxy filler...and then it's a go.... These boxes wound up being TIG'd on..will have a base and deck clean-up on the lathe along with the deck being grooved for a couple turns of copper wire...

Tom Garcia · Post by **Tom Garcia** » Sun Jan 03, 2010 7:05 pm

Hit the big sand blasting cabinet at a buddies garage today...made quick work of the case halves, jugs, and heads... Quick trip through the dishwasher and bake-dry in the oven...

Wife has already given up!

Couple coats of VHT silver caliper paint...

I dropped the lower case half and snapped off one of the bosses... Will have to break out the TIG again and repair it before I can paint it.

...then should be able to get the lower end together.

Will drill the reed mounting holes/tap..

Still have to decide which way I am going to go to move the ring locator pins on the pistons...

rngdng · Post by **rngdng** » Sun Jan 03, 2010 8:37 pm

I guess all of the porting you and Dave (and some others are doing) is beyond my understanding. It almost appears that you're just trying to get as many holes in there as possible.

Where are you guys getting your ideas?

Lane

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