How bad is the factory expansion chamber?

[seth6025]

Ok here is the deal....I am rebuilding my 1983 250r from frame up. It is still 250cc with honed cylinder and new rings. I am putting a Keihin 34mm carb, boyesen power reeds, and it has a fmf slip on already. From what I have seen the only option for a new expansion chamber is going to be a DG one. From my reading I see people say that DG is only a small improvement over the factory one. Mine is in good shape looking at it and the DG one for me in Canada is going to cost me 300 bucks. Do you guys think the factory one will be a big bottle neck in the system or do you think the 300 bucks on the DG is worth it in your opinions. Thanks for any info

[seth6025]

Here is a pic of the bike as of now all powder coated. Start putting back together tonight

[yaegerb]

Ok here is the deal....I am rebuilding my 1983 250r from frame up. It is still 250cc with honed cylinder and new rings. I am putting a Keihin 34mm carb, boyesen power reeds, and it has a fmf slip on already. From what I have seen the only option for a new expansion chamber is going to be a DG one. From my reading I see people say that DG is only a small improvement over the factory one. Mine is in good shape looking at it and the DG one for me in Canada is going to cost me 300 bucks. Do you guys think the factory one will be a big bottle neck in the system or do you think the 300 bucks on the DG is worth it in your opinions. Thanks for any info

Dg isn't the only option. How much are you willing to spend?

[seth6025]

Well I guess that depends...what are my other options? I have searched all over and the only other makes all seem to only fit the 85/86 models. Now you have me curious lol. What ones are you thinking? I guess I don't really wanna spend 800 or anything but....

[yaegerb]

Kenny Roberts or Jemco could make you a pipe and will have more performance than the DG. Yes, it will be around 5-800.

[barnett468]

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If I already had a silencer, and carb, and reeds like you do and had a stock cylinder head and only had $300.00 and wanted the biggest bang for the buck I could get, I would increase the compression by having the stock head modified or buy an old aftermarket head like a dg.

These bikes have fairly low compression in stock form and increasing the compression will basically increase the power everywhere but you then have to use premium gas . Since you already have a pipe, I would try it with that pipe and the higher compression and see how it ran before automatically buying another pipe . Just going from a stock silencer to a straight thru one will make a noticeable improvement.

Be sure to jet it properly before you start flogging it to keep it from seizing.



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

[seth6025]

Ok thanks for the info. Would you have any advise on what I would want a shop to do to the head I have now to make it better? I have it off right now waiting on a new set of rings. Would you be talking about port and polish that I read about on forums? Im kinda new to the internals of the motors so just wondering exactly what I would be asking a machine shop to do to it. And would having the head worked on change anything else or would it still be same gaskets bolt on and go type thing?

[seth6025]

Lol fair enough...well said. I will start with the smaller stuff and work my way up. Thanks for all the good info guys

[this old rz]

For a 83, I'd at this point certainlly keep it as clean & stock as possible which means "reliable"

Perhaps a skimming of the head to increase compression a little, most 2 strokes I've ever seen can benefit from this inexpensive mod.(others here whom are far mor familiar with the aircooled can liljey recommwnd how much to sgave off. Also always check to see if this hasnt been done prior to your ownership.
For a 83 if you want a lil bling and a lil better performance.
IMO a DG would be just fine.

The reason I say this was touched on above, if you want "substantial" performance increase, your far better suited to a 85 or newer machine.

Nothings more of a bummer than a 2 stroke thats been pooly ported tuned thsts a psin to start and fouls ugsand you cant enjoy it.
Even a 83 will be more than most riders ( of a certain age) can honestly ride in anger...safely

[christph]

I just made mods to my stock 84 ATC 250R in the past couple months and here is my experience. First, the DG pipe is much better than you have read. In fact, I probably read the same comments you have about the DG pipe but I got one anyway because that was the most reasonable option for now. I was surprised how much it improved the performance over the stock exhaust. I think the design may even be based on one of the team pipes back in the day. I can only go by pictures, but its shape and dimensions look identical to Team Honda's (see the Airfoolers website and the magazine section where they do a write up). Next, I added a DG sunburst high compression head. It is about 2 cc less than the stock head so I run 50/50 race and pump gas to avoid detonation, especially when hot. Wow, that was another kick in the pants. Next I installed a 34 mm Keihin from the 86 ATC 250R, a common upgrade for the 2nd generation (you can also use the one from the TRX 250R 86-89). Initially I tried a Mikuni 38 mm TM but it was too big; I lost too much bottom end. I wouldn't go larger than 36 mm without some porting. Lastly, I added a V-Force reed. With these upgrades my R has become a very impressive machine. Next I plan on cleaning up the ports and focusing on the suspension.

[this old rz]

I have to agree on any stock or mildly modified 2 stroke a DG or equivilant pipe of the day, should by all rights deliver better performance over stock. I would say DG was built/designed for a "optimum" pipe design that delivers a even power increase over a stock system..without becoming a pipey "top end race pipe. Just a good fair decent pipe. No... not the best, obviouslly one has to design a pipe with port calculations, head design and intended riding style and fuel.

A DG is a good "bolt on" pipe.

I dont know if this is factual or not, but I was told Harry Klemm was influential as a designer /tuner for DG and team Honda parts, the RD350-400 sunburst heads being what I was told in particular?? Could just be a wives tale?

[HondaRidr]

What's with all the lack of love for the foolers??? I have an 83 and love it. I have an old school dg (I believe), 38mm carb, Boyeson reeds, open airbox and a mildly ported cylinder. It is a very quick bike and 90 percent of the time will do anything that a liquid r will. As far as the new dg, I have no experience but I'm guessing you will get a nice boost in power over the very mellow stock pipe.

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[christph]

What's with all the lack of love for the foolers??? I have an 83 and love it. I have an old school dg (I believe), 38mm carb, Boyeson reeds, open airbox and a mildly ported cylinder. It is a very quick bike and 90 percent of the time will do anything that a liquid r will. As far as the new dg, I have no experience but I'm guessing you will get a nice boost in power over the very mellow stock pipe.

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I agree. The 1st generation engine has a lot of potential and can hold its own against the 2nd generation engine. In fact, I personally like the power delivery of my 84 over my 86 right now because the 84 has more of a hit like a 2 stroke should. Both the 84 and 86 have counterbalancers, but the 86 is so heavy I think it evens out the power delivery too much. Now, there are some things about the 2nd generation engine I like over the 1st. One, it has a 6 speed transmission, although the spacing of the 5 speed on the 1st generation isn't bad. Two, the liquid cooling of the 2nd generation keeps the operating temperatures more even. The 1st generation is prone to overheating at times, like when you have big loads at slow speeds, e.g. sand.

[yaegerb]

What's with all the lack of love for the foolers??? I have an 83 and love it. I have an old school dg (I believe), 38mm carb, Boyeson reeds, open airbox and a mildly ported cylinder. It is a very quick bike and 90 percent of the time will do anything that a liquid r will. As far as the new dg, I have no experience but I'm guessing you will get a nice boost in power over the very mellow stock pipe.

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Lack of love, I don't understand this comment?

I have been building foolers and liquids for longer than I can remember and each have the strong and weak points. The OP asked about the DG pipe.

Is it better than factory? Yes
Is it the best thing you can get? No, and for 300 bucks shipped to Canadia, that's ridiculous. For another 200 he could have a hand coned pipe, tuned, for what he's doing.

Or you have 2 other options below that are, IMO, better performance than a DG.

http://www.ebay.com/itm/1981-1982-HO...ZYjOjt&vxp=mtr

http://www.ebay.com/itm/82-atc-250r-...RYk~Ht&vxp=mtr

I have used DG multiple times and they aren't a bad pipe. I have seen better performance gains with others.

[christph]

Yeah, the Bassani is a great pipe, I have one on my 82. Unfortunately 1st generation Bassani will not fit on a 2nd generation R--I've tried it.