inlet 38mm
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good evening,
sorry if maybe it has nothing to do with it but I wanted to ask if anyone knows how and where to find an inlet for the dtr 1991 125 38mm...
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Ran a 38mm keihin carb on a 2001 DTR way back when:
https://www.youtube.com/watch?v=bOGAEzTaBgI
Just drilled the inlet manifold out and then lots of aggressive force.
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@calum really??? So the only thing to do is take the original manifold and enlarge it?
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With what did you dig the manifold?
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@dylandt219 So crude...hole saw
@calum
But in what sense? I don't understand with what you widened this hole, if I don't ask too much can you explain to me what tools you used and above all the procedure? -
@calum
But in what sense? I don't understand with what you widened this hole, if I don't ask too much can you explain to me what tools you used and above all the procedure?@dylandt219
If u have access to a 3d printer, or friends with one or somewhere u can get stuff 3d printed, that route would be better to go if u ever wanted to revert back to the old carb, im guessing youve already tried loads of heat to slip the carb in to the standard inlet?Ive otherwise heard people saying that the Cr125 inlet and reeds have the same bolt pattern but you will have to be creative about the read stuffers.
I could try and mock up a cad design in solidworks if u would be able to go the 3d printing route if u would be interested in that yourself. However im no cad wizard so i cant promise anything
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@dylandt219
If u have access to a 3d printer, or friends with one or somewhere u can get stuff 3d printed, that route would be better to go if u ever wanted to revert back to the old carb, im guessing youve already tried loads of heat to slip the carb in to the standard inlet?Ive otherwise heard people saying that the Cr125 inlet and reeds have the same bolt pattern but you will have to be creative about the read stuffers.
I could try and mock up a cad design in solidworks if u would be able to go the 3d printing route if u would be interested in that yourself. However im no cad wizard so i cant promise anything
@arild
anyway yes, I have already tried to heat the manifold to let the 38mm in but it just doesn't want to go in ...I had never heard of the story of the cr125 which has the same bolt pattern as the manifold
however yes I have a friend who has the 3d printer but he too is not very good at making projects so we had already discarded the idea at the start I tell you if you really want and above all time to create a serious project that works I will also be happy to pay you because I'm really looking for manifold for a lifetime to fit 38mm
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@DylanDT219 Ran that 38mm carb inlet setup for years daily driver no issues.
Just reamed out the inlet to a suitable size.
If you don't want to damage the inlet, then you can easily obtain 28-32mm inlet carb joiners. Just modify the joiner.
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@dylandt219
If u have access to a 3d printer, or friends with one or somewhere u can get stuff 3d printed, that route would be better to go if u ever wanted to revert back to the old carb, im guessing youve already tried loads of heat to slip the carb in to the standard inlet?Ive otherwise heard people saying that the Cr125 inlet and reeds have the same bolt pattern but you will have to be creative about the read stuffers.
I could try and mock up a cad design in solidworks if u would be able to go the 3d printing route if u would be interested in that yourself. However im no cad wizard so i cant promise anything
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@declan i dont have any of my own experience so im not sure, i saw a guy on facebook use a cr inlet to make his carb fit, he only mentioned that the reed stuffers where the only problem and nothing of the actual bolt pattern, but like i said i lack any personal experience in that matter
@DylanDT219
I can look at it a little tomorrow but i can promise nothing, im still just an apprentice when it comes to the 3d designing but ill give it a look -
A little off topic but what are you looking to achieve with a 38mm carb? It’s massively oversized for standard porting, I would be looking at more 30-32mm maximum
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@glynn123 I can't say that this DTR ran particularly well.
It DRANK fuel it was totally overkill and you'd probably have gotten better performance out of a smaller carb. It was 170cc mind.
@calum yeah I’d agree mate, even when I fitted and setup my 32mm I wasn’t all that convinced it made a huge difference, and massively reduced mpg haha. But ofcourse the benefits come with the other changes that were made, but if I’m honest the standard carb on these bikes is a cracker when it’s setup right.
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I’ve fitted a 34mm carb to a standard inlet, I put the inlet in the oven for 20 mins and used a thin smear of Castrol Grease, worked a treat!
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@declan i dont have any of my own experience so im not sure, i saw a guy on facebook use a cr inlet to make his carb fit, he only mentioned that the reed stuffers where the only problem and nothing of the actual bolt pattern, but like i said i lack any personal experience in that matter
@DylanDT219
I can look at it a little tomorrow but i can promise nothing, im still just an apprentice when it comes to the 3d designing but ill give it a look@arild okay go easy, let me know
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A little off topic but what are you looking to achieve with a 38mm carb? It’s massively oversized for standard porting, I would be looking at more 30-32mm maximum
@glynn123
I have a 170cc Athena that does not even do 100 km / h in addition to the fact that now we have elaborated the cylinder by opening the 38mm ports more I think it is a must -
@glynn123 I can't say that this DTR ran particularly well.
It DRANK fuel it was totally overkill and you'd probably have gotten better performance out of a smaller carb. It was 170cc mind.
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@calum
mhm I'm not particularly sure if a 38mm is too excessive, but as soon as I mount it I'll try it and I'll let you know@DylanDT219 the ports aren't the problem with the Athena kit. They aren't great but they aren't the problem. I will be writing a blog on this in the fullness of time, along with how you fix the Athena barrel and what it is like afterwards. But it's all in development now.
In short, it's the port timings not the port windows that are the problem.
Take the head off, or look up the exhaust port and rotate the crankshaft 360 degrees to see what I mean. It should be obvious.
Also bigger is not always better. The engine produces a finjte amount of vacuum pressure. A bigger carb reaults in losses of this oreasure. Loss of pressure results in loss of soeed which will negatively impact your performance. Don't go too big. Don't go too small. There is a middle ground. 34 is probably a little on the big side. 32mm is pretty sweet.
Always Originate, Never Pirate!
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@DylanDT219 the ports aren't the problem with the Athena kit. They aren't great but they aren't the problem. I will be writing a blog on this in the fullness of time, along with how you fix the Athena barrel and what it is like afterwards. But it's all in development now.
In short, it's the port timings not the port windows that are the problem.
Take the head off, or look up the exhaust port and rotate the crankshaft 360 degrees to see what I mean. It should be obvious.
Also bigger is not always better. The engine produces a finjte amount of vacuum pressure. A bigger carb reaults in losses of this oreasure. Loss of pressure results in loss of soeed which will negatively impact your performance. Don't go too big. Don't go too small. There is a middle ground. 34 is probably a little on the big side. 32mm is pretty sweet.
look maybe because here we have a different mechanics thought but put a 38mm on a 170cc athena which also has some design problems I don't see a problem in doing so, I repeat my dtr with the 170cc athena, carb of the 30mm, firebox + fmf and not it is not even 100 km / h. I prepared the cylinder together with a friend of mine who knows enough and we also prepared the engine block along with everything a zeltronic control unit, reed valve v-force 4 will also be added. I think a 32mm with all these things is underdeveloped for the components it will mount
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Right, okay cool. I am just trying to help.
I have been around these bikes for 13 years. I have seen how they tune. I have ran Athena 170 with 38mm carb and rode it daily. I linked a video of that bike on a flyby.
I am trying to give you my experience. Out of all the modifications I have done, the best I have got out of my bike is a ported 3mb with altered squish 32mm carb, underslung pipe and zeel.
It's not the carb as to why you can't do over 100
Always Originate, Never Pirate!
