Recommendations, boring, ballancing

[platinum2]

tuning isnt hard, you dont need electronic crap, its just extra bull to deal with
if the carbs were good, they worked well enough, my self i would go with mechanical flatslide something easy to use im sure you can figure it out you have done how much already
actually you could go with edelbrocks flat slide carbs, and there only 100 or so

[pete]

For me the electrickery is all a bit interesting and fun... I enjoy that stuff to a certain extent. My ability to read plugs is a little dodgy...

But you're both right, there's nothing wrong with sticking to the tried and true methods for getting tuning right

I can guarantee an experienced tuner would get better results with "feel" and plug chops than I ever would with the fanciest electrics...

[Mekanix]

Tps, map, egt, o2, iat, atmos press, all great to have. However, when the delivery system is still carbs and not FI its a learning curve to see what does what and what is important or not. Having a micro squirt system that maps all that and learns as it goes is awesome.

Id go for egt and o2 and tps for just carbs. That will tell you all you need to know.

But in the end Id just ride it anyways to know for sure.


I know you have to be wot for setting the main jet... But does the rpm matter? As in should you check it at 11000 or at 9000 or just somewhere before redline ? Or just when it stops pulling?

[Big Rich]

On CV carbs, rpm's are very important. If you think about it, you can hold it at WOT from 2000 rpm but it will only have the butterflies wide open - the slides haven't moved all the way up yet to allow the needle out of the way, so they are still "blocking" the main jets.

Most people will try to jet from the top down (main jets first, than the needles, etc). But on a rebuilt motor that needs broken in first, it's good to work from the bottom up instead so you aren't doing WOT plug chops on a fresh motor.

[Mekanix]

Yeah that's why I'm just going to jet it so that it feels alright for cruising around and progressively come on to it and check the plugs each time I get it up a bit higher.

I actually don't know where to start.

In theory the extra displacement means I would have to jet down but the extra flow and filters would mean jetting up.

I have 117.5 main's and 40 pilots in them now.
I have everything up to 150 to try. I might just throw those in to see what happens.

Now If I could just get to the bike :P


Blue bike is coming along. Its due for first oil change and check the valves. Also have some bad cam walk on the exhaust cam. Turns out as I was choosing my best cam's I picked the one that needed shimming :P

Then there is the seadoo to finish and vehicle inspection do at the end of the month :P

So little time, so much to do.

[ben2go]

I posted my jetting earlier in this post.It's what worked for me and I have the same basic set up as you.K&N lunch box and a flow thru muffler 40/142.5/no washers/10mm cut from the slide springs,and 3.5 turns on the mix screws.I have no hesitation any where in the rpm.A lot of GS twin guys complain about hesitation or slide lag at low rpm and starting from a stop.I don't have that.

[Mekanix]

I posted my jetting earlier in this post.It's what worked for me and I have the same basic set up as you.K&N lunch box and a flow thru muffler 40/142.5/no washers/10mm cut from the slide springs,and 3.5 turns on the mix screws.I have no hesitation any where in the rpm.A lot of GS twin guys complain about hesitation or slide lag at low rpm and starting from a stop.I don't have that.

I measured the 134 DJ jets and they are the closest to the 142.5... Hmm your onto something there :P Might swap them out for the 142's if i don't use them for the other bike.

[rapidray]

http://www.ebay.com/itm/2008-Suzuki-Rmz-250-Carburetor-Keihin-Carb-Fcr-37mm-throttle-07-09-rmz-250-/261232196372?pt=Motorcycles_Parts_Accessories&hash=item3cd2a6fb14&vxp=mtr

http://www.ebay.com/itm/Suzuki-Rmz-250-Carburetor-Keihin-37mm-FCR-Carb-2004-2007-2008-2009-Rm-z250-/111012162480?pt=Motorcycles_Parts_Accessories&hash=item19d8d72bb0&vxp=mtr

http://www.ebay.com/itm/2005-YZ250F-YZF-250-YZ-250F-carb-carburetor-fuel-gas-carby-keihin-37mm-fcr-03-07-/350808991318?pt=Motorcycles_Parts_Accessories&hash=item51add86656&vxp=mtr

http://www.ebay.com/itm/2010-KAWASAKI-KX250F-KEIHIN-37mm-FCR-CARBURETOR-KX-250F-KXF-2004-10-RMZ250-04-06-/161051582674?pt=Motorcycles_Parts_Accessories&hash=item257f6c20d2&vxp=mtr

http://www.ebay.com/itm/2009-Yamaha-YZ250F-YZ-250-Keihin-FCR-37mm-Carb-throttle-cables-06-07-08-09-/290889894259?pt=Motorcycles_Parts_Accessories&hash=item43ba638973&vxp=mtr

Just a few I found after looking for all of 5 minutes. Ray.

[Mekanix]

Have to build up the budget again to get those :P

Engine is going in this week. I finally got to the bike.

[Mekanix]

Engine is in the frame

Forgot to get some exhaust crush rings though

Only a few things left to do before first start.

Have to add the wiring for the new GS500 ignitor and coils.
I think I'll keep the original wiring and tuck it away.

[Chuck78]

I was really really impressed with the light weight and simple design of a set of early 90's GSXR600 Mikuni BST33 Slingshot flatslides that I got for about $50 shipped with a set of junker parts BST31's. Deals like that are out there, those carbs sell for $200 a rack for a 4 cylinder bike. If you could find a twin setup of those carbs (they came in a 34mm version that is more sought after and will bolt right up into a BS34 intake boot), I'm sure you'd be really set.

The phenolic flatslides are so darn light (the slides themselves, and yes - the carbs are substantially lighter overall as well), featherweight slides improve the throttle response and sensitivity drastically from the old big round aluminium slides on the BS32's ad BS34's. So your desire to move to some Slingshots is a very positive move. I'm curious about those Edelbrock carbs mentioned back in your post. Mechanical slides I think they were? I was under the impression that if a cylinder head intake port was designed for a CV carb, the port will be much larger and tuned for a CV style carb, and swapping a mechanical slide carb (smaller venturi due to less restriction - no butterfly valve) wouldn't be the best setup. Correct me if I'm wrong.

[Mekanix]

[pete]

Excellent! How long 'til first fire do you reckon?

[Mekanix]

This week id say. Can't decide if I want to use the gs500 ignitor or just throw the original back in. I have a spare 500 harness to hack as well. It just takes time to do.

I could just throw the pipes on and start it now if I swaped the old ignition plate back in.

I need to dedicate some time to I it.

I tried cranking it today. Killed the battery :-p. It was sitting for a month since I charged it. Not looking too good inside either.

Voltmeter droped to 5v while cranking and it didn't even make it around.

While it did crank over a few times I definitely noticed a way deeper tone from the headers.

Got an exhaust lined up as well for a two into one. Just have to build up funds.

[Mekanix]

I was really really impressed with the light weight and simple design of a set of early 90's GSXR600 Mikuni BST33 Slingshot flatslides that I got for about $50 shipped with a set of junker parts BST31's. Deals like that are out there, those carbs sell for $200 a rack for a 4 cylinder bike. If you could find a twin setup of those carbs (they came in a 34mm version that is more sought after and will bolt right up into a BS34 intake boot), I'm sure you'd be really set.

The phenolic flatslides are so darn light (the slides themselves, and yes - the carbs are substantially lighter overall as well), featherweight slides improve the throttle response and sensitivity drastically from the old big round aluminium slides on the BS32's ad BS34's. So your desire to move to some Slingshots is a very positive move. I'm curious about those Edelbrock carbs mentioned back in your post. Mechanical slides I think they were? I was under the impression that if a cylinder head intake port was designed for a CV carb, the port will be much larger and tuned for a CV style carb, and swapping a mechanical slide carb (smaller venturi due to less restriction - no butterfly valve) wouldn't be the best setup. Correct me if I'm wrong.

I'm building my spare set back up. Some Parts were needed for the blue bike. For now ill deal with the stock ones and keep getting parts. I'm always looking for deals but I have 3 projects coming together at the same time. That takes all my time and money

I did notice that the slingshots could flow more fuel very quickly if the slide holes were opened up a bit. Im more familiar with those than the other ones now.

I do know a few tricks for those though.
And I like how easy they are to work on :-)