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Easy-X
Super Spammer
Joined: 08 Mar 2019
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 Posted: 03:36 - 07 Dec 2025  Post subject: Interesting old dirt bike - Honda XL250r |
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https://www.youtube.com/watch?v=sUbPYRj3IeM
2vintage does his usual buy a bike, get it running. Bit of a weird one though, a typical single cylinder engine but dual carbs! Slow and fast running (or however you want to phrase it) as a mismatched pair 
One of those "I musta missed a meeting" technologies that I'd only ever seen on classic American V8 car engines. Basically shows how little I know about motorbikes!
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter |
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| stinkwheel |
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stinkwheel
Bovine Proctologist
Joined: 12 Jul 2004
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Posted: 10:08 - 07 Dec 2025  Post subject: |
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My MZ Baghira which had a Yamaha XTZ660 based engine had that.
A small slide carb in tandem with a big CV carb with no idle circuit. Up to about 1/4 throttle it ran on the slide carb only, then the linkage picked up the butterfly on the CV.
Worked well so it started easily and idled cleanly on the dinky little carb and had a very soft and controllable throttle response for slow speed, fiddly riding. Crack it open past 1/4 throttle and it changed it's tune in a mass of induction roar and big single silliness.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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| blurredman |
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blurredman
World Chat Champion
Joined: 18 Sep 2010
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| Posted: 12:00 - 07 Dec 2025 Post subject: |
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Quite common back then.
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CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S, 1979 MZ TS150.
Current: 1973 MZ ES250/2 - 18k, 1979 Suzuki TS185ER - 10k, 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (295cc) - 40k, 1989 MZ ETZ251 - 51k. |
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| virus |
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virus
World Chat Champion
Joined: 16 Aug 2006
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| Posted: 14:57 - 07 Dec 2025 Post subject: |
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| stinkwheel wrote: | My MZ Baghira which had a Yamaha XTZ660 based engine had that.
A small slide carb in tandem with a big CV carb with no idle circuit. Up to about 1/4 throttle it ran on the slide carb only, then the linkage picked up the butterfly on the CV.
Worked well so it started easily and idled cleanly on the dinky little carb and had a very soft and controllable throttle response for slow speed, fiddly riding. Crack it open past 1/4 throttle and it changed it's tune in a mass of induction roar and big single silliness. |
every now and then a basket case baghira draws my attention and it takes a lot of willpower to say no. something about the jekyl and hyde stle of carburetion seems like a lot of fun.
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own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance. |
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Easy-X
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| Posted: 15:21 - 07 Dec 2025 Post subject: |
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The balancing act for a single carb is always smaller = fast response, larger = moar powa  Why not have both I suppose.
A point in EFI's favour: it can easily simulate what two carbs like this would do.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter |
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stinkwheel
Bovine Proctologist
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| A100man |
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A100man
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| Posted: 12:52 - 11 Dec 2025 Post subject: |
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| stinkwheel wrote: | | virus wrote: |
every now and then a basket case baghira draws my attention and it takes a lot of willpower to say no. something about the jekyl and hyde stle of carburetion seems like a lot of fun. |
They were very well put together using top quality parts from well established manufacturers (WP shopck, marasocchi forks, grimecha brakes, ascerbis plastics). The only real complaint is they are a bit on the heavy side for what they are. |
Mine (Skorpion) gave me the heebeejeebees.. I lived in fear the carb(s) would play up. measuring oil level cos dry sump was nigh on impossible,
the primary drive nut and balancer scare stories gave me sleepless nights and an odd ticking developed that I swear wasn't there when I bought it..
.. big bro has an XT600 (aircooled version or engine) and has burst a blood vessel in his right leg trying to kick it over...
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Now: A100, GT250A, XJ598, FZ750
Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600 |
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