i usually build suzuki gt250's, but apart from water cooling one, i've done just about everything i can with them. so, having just aquired a pair of rd250 air cooled barrels and cylinder heads at a very reasonable price, i thought: why not fit them to the gt250 bottom end to give me [another] mongrel gt250 reed valve engine? i know it will be a lot of work, such as filling and redrilling the bolt holes, but i've done it before to fit some gt250a barrels on a ramair bottom end. also had them bored out to 58mm to give me a gt285 8) so i know it's do-able. don't ask why i should want to do such a thing, it's because i can [and mad as a hatter] - and hopefully nobody else has done it :celebrate:
cheers, gil.
Go for it. I did try to convince someone to fit a pair of RD 350 or 400 barrels on a set of 315/350 cases. That has to be an easy path to 60hp at the rear wheel. :celebrate:
it has been done. you can fit 350 cyls as well if you can fly cut the case. :whistle:
hi mate, thanks for that. if there's a write up to it anywhere then i'd love to read it. it's not as easy a conversion as it was at first glance, but should keep me out of trouble for a while. main problem being the stud spacing. ;D
cheers, gil.
i was asked to do it about 12 years ago, i never saw the benefit over remounting an rd motor in a gt chassis, but its been done (not by me, wasnt worth my time). or reeding a GT250 topend and porting the snot out of it. . :twocents:
hi mate, the original plan was to convert the gt250 top end to reed valve, using [cheap] rd350 reeds and rubber carb manifold, plus a couple of lumps of ali, milled out to take the reeds. but in my infinite wisdom i decided that using the rd250 top end was an easier choice. perhaps i ought to go back to plan 'a'?
cheers, gil.
i would, tbh, its easier i think in the long run. I've milled a set of GT250 cyls for reeds for another guy,(Tom Garcia) he used some 8 petal snowmobiles reeds on it, supposedly worked out great.
hi mate [again]. do you have any photo's of the gt barrels reed conversion? just to give me an idea on where to start. many thanks if you can ;D
cheers, gil.
i might have pics of me milling the back off them, maybe. i didnt add the reeds, tom did that himself.
any pics would be welcome before i start milling chunks out of a good set of barrels, or even a drawing would help. the only bit that baffles me atm is the gt inlet port, which is standard at 26mm and round, which reall won't be condusive to good flow from the reeds' thanks again for your input ;D
cheers, gil.
i only have the 2 pics. i just milled the back flat, he did the porting and addition of reeds. i know he added tranfer ports and opened it up quite a bit.
note the intake oiling hole is still intact.
(http://www.2strokeworld.net/wp-content/uploads/gt250cyls/DSC02279.jpg)
(http://www.2strokeworld.net/wp-content/uploads/gt250cyls/DSC02280.jpg)
Here's one I grabbed from Tom's thread way back when
thanks for the photo's - much appreciated. i came up with a different idea. don't know why i never thought of it before, but there's a stockist in greater manchester somewhere that sells aluminium square box section in 60mm x 60mm x 5mm wall. that makes the i.d. 50mm and the reed valves are 50mm square - the reeds themselves. cut to right length and angle, make the end flanges and have them welded on. job's a gudun as they say. it will save an awful lot of milling out. just hope they'll let me buy just a short piece and not a 5 metre length minimum :P i have emailed them with my plea, so fingers crossed. it will cut the machining time down by hours. i could have used 57mm or 21/4" in imperial, with 3.2mm wall, but can't find anybody that stocks 21/4 square and 10 swg wall. i'll keep looking, if this wifi stays on. waiting for it to come back on so i can post this. why don't my wifi work properly when it's raining? (rofl)
cheers, gil.
i mean, it only took like 15 minutes per cyl in the bridgeport, wasn't hard to do.
thats cool you have that pic, i lost it a long time ago. he just told me 'mill it flat' i was like 'ok' and chips went flying. :science:
dead thread revisited ;D after 7 months this is what i came up with. and this morning it ran properly for the first time. i installed it in an old gt250 frame, wired it up and fitted a temporary fuel tank. all that's left now is everything else. photo is mid build, until i can find the later photo's 8)
cheers, gil.
gt250 ramair reed conversion:
(https://i.postimg.cc/dts6bRgj/reedyx2.jpg) (https://postimages.org/)
I like that . I love reed conversions . I do alot of them here is a manifold I recently made and produced for early Honda elsinore 125s
Here is the prototype installed
oops ! that wa the wrong pic , same manifold but on a Hodaka 175 . This pic is on the Honda
looks similar to ones i did for S series kawis a few years ago:
(http://www.2strokeworld.net/wp-content/uploads/S2s-all/Blue-73-s2/intake-proto/reed-protoypes-alum-2.jpg)
then the 73 h1 i had. ran 2 boost ports up the back of the cyl :
(http://www.2strokeworld.net/wp-content/uploads/other-bikes-related/my-old-bikes/frog/h1-reedcages1.jpg)
would up using chariot performance cnc'd banshee cages and PJ34's with one off dencos from Jim Hobbs. Man this bike made/makes gobs of useable power.
(http://www.2strokeworld.net/wp-content/uploads/other-bikes-related/my-old-bikes/frog/DSC04859.jpg)
reed conversions are good. :metal:
very nice work . I have 4 different manifolds that I have made and produced and apply them to many applications with use of different mounting plates Here is another one
here is the same manifold I use on Polaris snow machines. I have used them on Suzuki Honda cr 250s Bultacos Hodakas and more
Quote from: Gil Gallad on July 13, 2020, 08:56:29 AM
dead thread revisited ;D after 7 months this is what i came up with. and this morning it ran properly for the first time. i installed it in an old gt250 frame, wired it up and fitted a temporary fuel tank. all that's left now is everything else. photo is mid build, until i can find the later photo's 8)
cheers, gil.
gt250 ramair reed conversion:
(https://i.postimg.cc/dts6bRgj/reedyx2.jpg) (https://postimages.org/)
Spectacular :cheerleader:
That Suzuki engine looks great with reeds!
The H1.. :drool:
heads now off for vapour blasting, but i took this photo before i took them off. boost bottle fitted, but i just guessed the measurements - 180mm long and 24mm i.d. does it make a difference? not got a clue, but it still fires up and runs. think a trip to a dyno might help ;D
cheers, gil.
boost bottle:
(https://i.postimg.cc/NGrhWfX3/reedbuildx33.jpg) (https://postimages.org/)
ditch the emgos, at least run all foam ones.
hi mate, they were supposed to be here last friday, but i'm doing a diana ross again - i'm still waiting :evil2: i just put those crappy ones on just to keep anything from going down the carbs. i always use the foam sort now ;D
cheers, gil.
:cheerleader: :cheerleader:
Quote from: racerclam on July 13, 2020, 04:55:56 PM
here is the same manifold I use on Polaris snow machines. I have used them on Suzuki Honda cr 250s Bultacos Hodakas and more
Those look interesting.
I know this is waaaay off topic (for real!), but I grew up in area where they were always called them "snowmobiles." This is probably a fairly common term I would think... Then I lived in Canada for while, and I've since made many friends from Canada, border states, as well as Alaska, and people from these places all seemingly call them "snow machines." This vernacular was odd to me at first. As a result, I get real romantic about that term. It just reminds me of all the friends I've made in my travels.
Anyways, continue on that sweet manifold talk.
I have chopped up a couple of sets of Arctic Cat and Polaris snow machine crankcases to harvest their organs (reed boxes). I also have a set of 34mm zinc small body carbs from a snow machine.
Snow machine is like the culturally proper term. But Michiganders call them sleds, sleighs, and snowmobiles. If you say snow machine here you sound snobby lol.
problems, problems :bang: ok, this is what i've got: home made reed cage [pictured elsewhere] with rd350 lc reeds in it, cheapo ones, but hey ho. i got the engine running using these reeds, so i decided to change the petals for 0.5mm thick carbon fibre petals. my problem is, now the engine won't even fire, as though no fuel is getting through. anybody with more experience of reeds [which is probably half the known world] think these petals are too thick? should i try 0.4mm or even 0.3mm? basically i'm at a loss with this one ;D
cheers, gil.
Quote from: Gil Gallad on August 16, 2020, 04:57:01 PM
problems, problems :bang: ok, this is what i've got: home made reed cage [pictured elsewhere] with rd350 lc reeds in it, cheapo ones, but hey ho. i got the engine running using these reeds, so i decided to change the petals for 0.5mm thick carbon fibre petals. my problem is, now the engine won't even fire, as though no fuel is getting through. anybody with more experience of reeds [which is probably half the known world] think these petals are too thick? should i try 0.4mm or even 0.3mm? basically i'm at a loss with this one ;D
cheers, gil.
Mmm. Insufficient vacuum could be a culprit, but that negative pressure has to translate somewhere.. so a reed not opening could be an issue. However, I would think you have an issue of a reed not sealing. No seal means no pressure building in the lower end to send fuel where it needs to be.
hi mate, thanks for the reply. when i fitted the petals it was a bright, sunny day [rarity in england, i know] and i held the reed cages up to the sunlight, checking for any gaps. there definitely weren't any. lack of vacuum is a thought though. newly rebuilt crank - new seals etc. rebored barrels and new piston kits, so should have decent vacuum. perhaps a t250/gt250 hybrid engine just isn't supposed to have reeds fitted? the thing is though, with the cheap chinese petals in it ran fine, but they were thinner ;D
cheers, gil.
I don't know, Gil. It seems like you suspect the reeds, so why not change back to the first set? It should be a pretty quick and easy test to perform.
Otherwise, make sure you are getting air, fuel, and spark.
Quote from: sav0r on August 17, 2020, 09:44:19 AM
I don't know, Gil. It seems like you suspect the reeds, so why not change back to the first set? It should be a pretty quick and easy test to perform.
Otherwise, make sure you are getting air, fuel, and spark.
^^^^^^^this^^^^^^
i did exactly that and got an even stranger phenomenon :umm: can't remember if i've posted this before, but until i've built the headers for this engine i've just been using a pair of standard gt250 exhausts. so, i rebuilt the reeds, carbs on etc, and left the exhausts off. she went first kick and revved real nice - albeit a bit loud. i fitted the exhausts and kicked and kicked - nothing, wouldn't even pop. thinking i might have fouled the plugs i swapped them for a new pair. kicked and kicked - even less, no pop, no bang, no nothing. so i took the exhausts off again. kicked her over and she went first kick. i know the exhausts are clear, so i can't blame them. so the question is wtf do i blame? ;D
cheers, gil.
p.s. thanks for the suggestions, btw.
Gil is killing it!
Love the boost bottle you made! Measurements of the cooper pipes you used?
(https://i.postimg.cc/NGrhWfX3/reedbuildx33.jpg)
Quote from: Gil Gallad on August 18, 2020, 06:40:07 AM
i did exactly that and got an even stranger phenomenon :umm: can't remember if i've posted this before, but until i've built the headers for this engine i've just been using a pair of standard gt250 exhausts. so, i rebuilt the reeds, carbs on etc, and left the exhausts off. she went first kick and revved real nice - albeit a bit loud. i fitted the exhausts and kicked and kicked - nothing, wouldn't even pop. thinking i might have fouled the plugs i swapped them for a new pair. kicked and kicked - even less, no pop, no bang, no nothing. so i took the exhausts off again. kicked her over and she went first kick. i know the exhausts are clear, so i can't blame them. so the question is wtf do i blame? ;D
cheers, gil.
p.s. thanks for the suggestions, btw.
A couple of thoughts. Carbon fiber reeds are much stiffer than fiberglass and are great for high RPM motors, but are harder to crack open. I forget what reed boxes you are using but a large intake volume will make it harder to start too.
With the pipes, that's interesting and may be a function of back pressure. There's not much useful information on the pressure in an exhaust - outside of pressure wave effects, but all exhausts run with an average pressure. Small stingers increase that pressure slightly and stock exhausts tend to be higher because of the sound dampening measures inside.
I'd speculate that the combination of high (relatively) exhaust pressure plus stiff reeds are working to keep the reeds basically shut. Try removing teh baffle tubes and see how that works and try softer reeds until you get some decent chanbers that send a nice negative pressure wave back to drop cylinder and crankcase pressure sufficiently.
thanks for the advice teazer, much appreciated. looks like i'd better get the headers made up pretty damned quick, then i might get somewhere :haw:
quocle, i don't know if this boost bottle works properly yet, only running the engine will prove one way or the other, but dimensions of copper pipe are: the top bit is 28mm pipe x 180mm long with 2 blanking caps on it. the legs are 15mm pipe x 45mm. plus i hope you're good at soldering ;D
cheers, gil.
all in all and from what i've read and researched, the figures i could do with as a base setting are standard ramair gt250 inlet, transfer and exhaust durations in degrees. then the same for the x7, which was virtually the same engine but had reed valves fitted. or even throw in a set of figures for the rg250, in essence again the same engine, but water cooled. all similar engines, but with a vast difference in power, and none of them used pistons with windows in them. i'm either looking in the wrong place or these figures don't exist, because i'm buggered if i can find them ;D
cheers, gil.
p.s. sorry i don't know the designation of the x7250 or the rg250 over the pond :umm:
Neither was available in the US. Perhaps Canadians got them but I doubt it.
IIRC, RG250 had piston port intakes but supplemented by a small crankcase reed. They were not the same as say and RD250/350 design. In some ways they were ahead of the curve with crankcase reeds. Fortunately it was easy to open up RG250 reed passages and that really seemed to improve them.
I don't remember the port layout but they had boost ports IIRC. TR500 Mk111 was also piston ported with cast in boost ports. Very interesting design as I recall.
Our RG250 was way faster than our stock(ish) RD400 but that may have been more to do with infinitely better handling and brakes.
having a lot of problems with this sob. i rebuilt it back to how i had it originally. ignition timing stayed the same, and the only thing i changed was the pilot jets, as i didn't think it was getting enough fuel at start up. now the only things it does are kick back and afterfire. there's fuel getting through, there's good sparks [using b6es while it's on the bench. i've tried it with b8es plugs and it's just the same. kickback and/or afterfire. any suggestions? i'd be most grateful ;D
cheers, gil.
p.s. pilot jets went up from #25 to #30
kicking back is usually a sign of too much advance or really lean mixture, but usually advance.
Try checking it with a degree wheel and spark plug tester or plug wire 10mm from the motor and see if it's firing when you think it should be.
Did you go back to the softer/thinner reed petals or is this with the same carbon fiber reeds?
I had the same issue with my RD when I kicked it over and it was too advanced.
thanks for the replies. so, after seeing a crack in the right side crankcase, right under and up to the base of the barrel i decided to take the engine out and put another bottom end in it. luckily i've got a few engines to play with. put the reed valve barrels etc on - the ones with the original thin reed petals - and kicked her over. afterfire. afterfire. afterfire. as well as kicking back. so i retarded the ignition a tad. still the same. so i retarded the ignition a lot. to the point of it shouldn't really run. then i was going to advance it slowly, degree by degree. BUT, it went first kick. amazing. still a bit blubbery when the revs drop, but it's running. the only problem i have now is the right cylinder is running a lot hotter than the left. electronic ignition with magnets at 180 degrees. i know i'll need to advance it a bit more, but heat on one side is baffling me. i'd know what to do if it was a f*ur stroke ;D
cheers, gil.
p.s. thanks again for the help.
is it one pickup 2 triggers? thats very hard to get correct. id baseline with points if you have them, then swap it over. 2 pickups 1 trigger. Ive been bit bad by ignitions before.
hi mate, you've seen my electronic ignition set up. same as a fiat 500 8) one pick-up and a red rotor ring on the end of the crank bolt. red rotor ring has 2 magnets in it at 180 degrees apart. i hate points, which is why i began experimenting with this system about 10 years ago. i fit it to all my gt engines, and a dt, an rg, even my old ajs 250csr has it. i run a one into 2 cbr600 coil - one coil and 2 ht leads. works perfectly and i have a box full of points, condensors and cams to prove it ;D
cheers, gil.
I get it, ive made plenty of my own.
but we all miss things on occasion, parts go bad, etc. . i'm just saying, establishing a baseline is just good diagnostics.