Reed Spacer, Get rid of it?

[gandgracing]

Didn't find a whole lot of info on this. I'm pretty much racing all top end. Is the reed spacer more for mx or what. I race drags and hillclimbs. I'm running one now but have seen some talk about you dont want the extra crankcase volume. Any drag racers out there that have tried with and without?

[LONG-ROD]

Not 100% on this but most companies that make reeds have found no gain or improvment by running these, the just make attaching a 39 mm carb much easier to the stock air box. The bigger carbs must be a little slimmer.

[87R_Racer]

Yeah I could tell no difference with one or without one.

[mxduner]

they came in handy when i went to the 310 prox cylinder and a rad valve, but i never rode this setup before to tell you if it made a difference.

[C-LEIGH RACING]

In testing over the years, the reed spacer will mellow the hit just a very small amount when the engine jumps onto the pipe.

Like if your cylinder is ported upper midrange or drag with pipe to match & has a light switch effect jumping on the pipe, you can, if your good enough, feel just a small amount of difference in how quick the jump is.

For drag, you want that BIG carb close as you can get it to the reed cage & stiff reeds that will respond fast at high rpm with no flutter.
Neil

[All250R]

Like Neil said, the more elastic air that is in the tract, the slower the response is. Think of tying an elastic cord to a door handle and tugging. The longer the cord, the slower the response. Air is elastic too and so responds to "tugging" similarly. When people say it mellows the hit in the tuned pipe, my personal theory is that it's reducing hp in that part of the rpm range. Some volume in the crankcase is needed if you want a broader power range, than say if you're building a roadrace engine with high hp numbers required, but too much volume I imagine will reduce power everywhere as the signal to the carb will meter too weakly.

I don't have the numbers in front of me, but the reed spacer adds a sizeable amount of cc's of air to the crankcase. The base spacer plate adds a comparable amount. I want to say combined you're around 100cc's extra (I'll try to remember to post these numbers). On a 250cc displacement motor, I figure that's a decent amount added to the elastic property of intake suction.

The PWK carb is not slimmer, it has a larger diameter requiring a bigger boot. The CR boot that fits the carb is closer to the reed petals (reducing air cc's) by about 1/2" than the TRX boot so creating a problem with the carb meeting with the stock airbox location. So if you're like me, you ran a spacer rather than disconnecting the box and hanging it with a zip tie or something...

I wanted to get rid of the spacer myself so I had a shop recently fab some airboxess-less air brackets that uses the stock tabs and lets you get rid of the spacer by moving the carb and tract forward 1/2". This lets you can get rid of the extra crankcase volume just because you wanted a carb more in line with a high output 250cc engine than the 34 PJ. I can post a pic or PM if anyone is interested in getting rid of their reed spacer. it's an open air fliter solution though. Prefilters help quite a bit with dust and light water tho. Getting rid of the spacer eliminates the extra reed gasket too which is a nice bonus.

[gandgracing]

Alot of go info. I think I will give it a try without the spacer.

[2muchquad]

I have run one before and found a bit more low mid grunt with a tad loss of throttle response but it does seem to help the motor pull the next gear a bit quicker,results may vary though..

[trx310R#24]

o an dont run belray gas in your gas if you like your bike to run..

[C-LEIGH RACING]

Originally posted by trx310R#24
o an dont run belray gas in your gas if you like your bike to run..

Whats wrong with Belray gas, or did you mean Belray oil. Please explain the problem.
Neil

[All250R]

Originally posted by C-LEIGH RACING
Whats wrong with Belray gas, or did you mean Belray oil. Please explain the problem.
Neil
He didn't offer much of an explanation about his reed spacer observations and the rest didn't have anything to do with the topic of this post so I'd be plesantly surprised if he has a sound observation to offer us.

[C-LEIGH RACING]

Yeah :D , you know I guess thats the bad thing about getting old, you just seen & done more then alot.
God, if I had 50 sent for every once of Belray I run through them ol Yamahas I would be rich son.

Now you want a oil that will get folks attention, get a pint of that Blendzall green label. Just the smell of it you'll think you got 10 more hp & about swair it has.
Neil

[trx310R#24]

Originally posted by C-LEIGH RACING
Yeah :D , you know I guess thats the bad thing about getting old, you just seen & done more then alot.
God, if I had 50 sent for every once of Belray I run through them ol Yamahas I would be rich son.

Now you want a oil that will get folks attention, get a pint of that Blendzall green label. Just the smell of it you'll think you got 10 more hp & about swair it has.
Neil

motul smells really good to i all ways runned belray till one day i was 15 i walked in the dealer to get a plug an oil an the owner said im buying to many plugs he told me to try motul at 32:1 an i dont have to buy a plug everyday anymore... i ran belray 32:1 an it burns my plugs always has... i love the belray trans oil.... then again i change it so much that it dont matter lol i think ill try blendzall tho