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TOPIC: boost porting of 1971 DT1E250

boost porting of 1971 DT1E250 07 Feb 2018 20:28 #1

  • RacerClam
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Thought I would share this piston port 250 I just completed porting plus adding a boost port , Ive done a bunch with this method on other machines with good results , adding this port allows the hooking of the rear transfer port exits since scavenging is now handled by the boost port. A great power booster combo

Rich





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racerclam
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boost porting of 1971 DT1E250 08 Feb 2018 05:18 #2

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Nice work!

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1970 DT1-C Grand Prix race bike
1970 DT1-C Dirt bike
1968 Honda CL90
1971 Honda Sl 125
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1967 Moto Guzzi V700

boost porting of 1971 DT1E250 08 Feb 2018 10:38 #3

  • RacerClam
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Thanks Tom, Got yours running yet ?

Rich

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racerclam

boost porting of 1971 DT1E250 08 Feb 2018 11:29 #4

  • RTD2
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Nice work Rich, I have to figure out what I am going to do with my 71 DT1 MX engine with the enduro cylinder. I have a 32mm carb, GYT kit head and pipe, but stock porting. I will be in touch later.

As a reminder you did the DT1 cases for me, beautiful job, I am getting close to finishing the bike they were for (70 DT1 MX).

Mike

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68 DT1, 70 DT1C MX, 71 CT1C, 71 RT1B, 71 DT1E MX, 73 AT3MX, 70 Husqvarna 250 Cross, 57 Matchless G80CS, 76 Honda Elsinore; 2015 Yamaha FZ-09

boost porting of 1971 DT1E250 08 Feb 2018 11:34 #5

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It's ready to run but the pipe is still a few weeks from being complete. A DG pipe donated to me by darinm (a member here) should be here tomorrow so I thought I'd throw that on just to run her down the road. I'm not planning on doing any jet changes or anything, just want to run the rings in a bit & hear her go Zzzzzzziiiiiiiiing :)

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1970 DT1-C Grand Prix race bike
1970 DT1-C Dirt bike
1968 Honda CL90
1971 Honda Sl 125
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1967 Moto Guzzi V700
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boost porting of 1971 DT1E250 08 Feb 2018 12:55 #6

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I must be loosing it or still have a 'lot to learn'--[that one] but doesn't it need to be controlled by reed valve like a "72 model to run that boost port?, so conversely, could i run a 'non reed' piston in my DT2 & 'No' reed cage & have a 'rocket'--well a std rocket not a go fast dt2mx one. Or am i way off the case, sorry. Very interesting all this. Thanks for posting. ps i know the dt1 & dt2 have different gudgeon heights in the piston--& different rod length, but just saying!!.
ps, or am i not looking at the picture right.
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Last Edit: by RT325.

boost porting of 1971 DT1E250 08 Feb 2018 13:12 #7

  • RacerClam
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no reed needed here , notice the boost port is not connected to the intake port ! because of the epoxy bulb , and the port id fed by a single horizontal hole below the ring land at bdc

Rich
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boost porting of 1971 DT1E250 08 Feb 2018 13:14 #8

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RTD2
can you possibly post a picture of your GYT kit head combustion chamber here , I want o identify the head I have here , customer thinks it is one but I don't think so

Rich

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racerclam

boost porting of 1971 DT1E250 08 Feb 2018 13:34 #9

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Ok, thanks for the quick reply.

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boost porting of 1971 DT1E250 08 Feb 2018 14:14 #10

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Here's one I have rich. It's either a dt1mx or a gyt. I think it's a gyt but I'm sure someone else will know for sure
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The Oil burners: 1973 DT-250, 1966 YM-1 305, 1966 YSD3, YZ-105
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