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joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
48 minutes ago I reached out on facebook, and a guy there got a hold of the guy from PFR. We are in contact now, and he's doing a pipe next week! I'm beyond excited! I remember a dyno test from the 80's between pipes. I don't remember the magazine, maybe Dirt Rider? The DG pipe made less power than the stock pipe...
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450exc115 Liked a reply to forum topic Building a RACE 1981 YZ 250, have a few questions.
11/2/2026 3:09am
Rich at Dynoport will make a custom exhaust if you want him too or at least he use to do it. Not sure of the cost but he'll also setup for what ever power spread you want. I know your in Upstate NY but I'm not sure how far he is from you as he'll most likely want the bike. Give him a call (315) 253-9631 I've always found the DG stuff hard to jet, both the YZ400 and YZ465 I had ran better on stock pipes than the DG that came with them. The 400 DG split at the...
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RDnutz Liked a reply to forum topic Building a RACE 1981 YZ 250, have a few questions.
10/31/2026 1:51pm
DOH! totally missed that reading your posts 🙃 IIRC the guy that owned Maicos Only had bought the PFR business and it stayed real busy and always behind on deliveries. He seemed a little prickly to deal with. In our 100cc Vintage Series he chose "4Q" as his number 😆 On last 2 of my 3 YZ250H bikes over time I used DG full exhaust systems and never had a performance problem with them. Never did more than seat of the pants testing vs stock though. My stockers were beat up and DG was quickest and cheapest way for me...
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joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
1 day ago I'm on eBay all day looking lol. There are stock pipes that pop up here and there. I already have the stock pipe but it has a few dents and a small split in it. Plus guys want $250+ for a stock pipe, that you can't really see up close. I don't know of any other companies that make vintage...
joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
1 day ago That's the place I called. They don't have them in stock.
joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
10/30/2026 1:26pm I'm not having much luck sourcing a pipe/silencer for the bike. VMX sells a DG kit but I really want the PFR stuff. I called AMS Racing as they have them on their website but he said they aren't in stock and the owner of PFR moved his shop, and hasn't gotten back up to speed as of yet. I...
RDnutz Liked a reply to forum topic Building a RACE 1981 YZ 250, have a few questions.
10/30/2026 1:07pm
glad you're sorting out what actually belongs on that model stock from factory as that's a good baseline to work up from. 1 thing I forgot to mention was that 1981 also came with the boost bottle, which I couldn't see in your video. Your intake manifold would have a special spigot on top where the hose to boost bottle connects. Most people didn't have the patience (or skill?) to properly jet and tune with the boost bottle system on there and removed them and used the 1980 intake manifold instead. The forks look similar to Yamahas of the era...
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Bluelion Liked a reply to forum topic 1977 Mugen 125 # 12 Steve Wise replica build
10/24/2026 2:18pm
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joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
10/15/2026 6:28pm It's 10.8lbs with the bushings still installed and the shock bolt attached.
joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
10/14/2026 5:06pm It's very light. I'll try to get it weighed this weekend, when I'm out there. It's honestly about the same weight as a traditional linkage type swingarm from a newer bike.
Oldschool Liked a reply to forum topic Building a RACE 1981 YZ 250, have a few questions.
10/14/2026 5:05pm
If you have the Swing arm off at one point.... can you weigh that mother of all Swing Arms ! ( I believe the 250 & 400 are identical )...
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joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
10/14/2026 5:04pm Funny story is that I traded an 88 YZ 250 for the 81 lol. The 88 was a hot mess though. I think I'm going to go with a dedicated drum brake fork setup as I don't want to ruffle any feathers at the race. Some guys can really scrutinize the rules and cry foul when you start to back...
450exc115 Liked a reply to forum topic Building a RACE 1981 YZ 250, have a few questions.
10/14/2026 4:56pm
81 YZ250 is a great bike. Biggest improvement would be either a vintage fox twin clicker shock or Racetech will make you a brand new modern like shock for it. I built my own version of the fox shock but the rebound circuit on the shock is just an orifice setup and not as nice as what Fox and Racetech can provided. If you are really going to make a bracket for a disk brake fork might as well find a cartridge fork to use. There are a few places that make brackets for the Honda 43mm forks that come...
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joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
10/12/2026 4:17pm I'm currently on the hunt for some parts lol. I need 43mm forks, triples, front and rear wheels, and possible a swingarm. Ideally I'd like to find a YZ 465 roller, as it would have everything I need. I did find a 1984 YZ 250 for cheap, that will have everything I need, but will have the stupid Z-spoke hubs.I...
RDnutz Liked a reply to forum topic Building a RACE 1981 YZ 250, have a few questions.
10/11/2026 11:02am
I was well into VMX by early 2000s and started with old 1st gen MONOshocks I grew up with. Then the competitiveness and class hopping bug got me. More experienced vet guys said always try to get last eligible year of any class you want to race in. I found a smoking deal on 1981 250h by accident on CL a couple miles from me for $150.00. I did mechanical refurb and cosmetics and added DG exhaust system, reeds, gently cleaned up ports, etc. It was a blast to ride & race! Light in the front end and quick off...
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joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
10/11/2026 3:00am The intake boot has been replaced at some point as it has no outlet for the bottle. My 490 has the setup on it. I can still get new intakes with the outlet on them, and I'm sure I can find the "bottle" as I believe they are the same from model to model. The hose should be easy to...
joelster Added a reply to Building a RACE 1981 YZ 250, have a few questions.
10/10/2026 1:42pm Upon further examination the bike is a hodge podge of assorted parts. The frame is legit 1981, as is the engine. The wheels are DID wheels date stamped late 78, so likely off of a 1979 YZ. I'll be on the lookout for a YZ 465 parts bike lol. I can't identify what forks it actually came with. They are...
RDnutz Liked a reply to forum topic Building a RACE 1981 YZ 250, have a few questions.
10/10/2026 4:27am
as others commented in Youtube, the 1981 4V3 did come standard with Gold rims. Also 43 mm forks with DLS (at least later in model year) and trans was changed to 5 speed instead of 6 like 1980. If that bike is a former racer it could be a bitsa with parts from both 80 & 81. They are a blast to ride/race but had some issues like the OEM ignition failures- which was already upgraded on yours.
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joelster Started a new thread Building a RACE 1981 YZ 250, have a few questions.
10/9/2026 4:30pm I have a local track near me called Zoar Valley MX Park. Once a year they host an incredible event, and they've recently added 2 $$$$$$$$$$$ classes. One is a 125GP and the other is a 250GP. Rules are pretty simple, air-cooled, drum brakes, bike had to be equipped from the factory with them, you can't back-date any bikes. The...
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