Hi there,

today I kicked the new engine with Dave's sleeper pipe for the first time.
Here is a first Youtube sound check.



With kind regards
Franjo

1975 Yamaha 400 enduro are still taking orders thank you Al renfrow

nice bike

Rich

Franjo sounds great......I definitely hear the signature "Sleeper Pipe" crackle !

Do you have a ride update for us on your beautiful DT2 ?

We are currently taking orders for new Sleeper Pipes

Here's the current price list

1969-1973 CT175 $199. usd
1969-1973 DT250/RT360 $229.
1974 DT250/DT360 $239
1975-1976 DT250/DT400 $239.

Misc pipe repairs -time & materials
customer is responsible for all shipping charges

Thanks Everyone

Do you make a pipe for a 1978 DT400E? If yes how much?
Cheers, bob

Sorry we don't offer the Sleeper Pipe mod for that pipe because of its design.

the best performance improvement on a 1978 DT400 is look into a performance silencer or mod the existing silencer to flow better. it will however lean out the jetting. I know of a guy that put on a FMF Turbine Core II universal silencer on his 1978 DT400 and while the bike ran like a raped primate it caused severe overheating. if you go that route I would look at a richer needle jet and jet needle and tune the pilot Jet and main jet as needed. it would be better to find a 34 mm Mikuni from Mikuni themselves and set it up close to those jets found on a 1978 stock DT400 carb and work from there. HVC Cycles sells a oil injection spigot that can be installed on the aftermarket Mikuni carb.

Makotosun found this problem years ago finding out the stock silencer is severely choked. he modded his stock silencer on I think a 1977 DT400D and it really brought the bike to life. the stock pipe itself on the larger bore late 1970's was actually pretty good, it was through the silencer itself that reduced the short circuiting of the transfer ports and exhaust port for the sake of emissions during that time.

for the best case scenario I would remove the pipe and burn it out for good measure then burn out the silencer and mod it for better flow.
I heard the jet needle is not adjustable on the 1977 through 1978 DT400, you can make some shims and slide them on the jet needle which will raise the needle fattening it up. you can get a great performance improvement for nearly free!
I would start with shims that are very slim and add more if needed or add a thicker shim if needed. might also get a TTO spark plug temp gauge to help with the tuning and keep a eye on your engine temps.

the jet needle mod might make the main jet too rich, you might be able to find a number or 2 lower main jet. do this only if needed and you have a TTO temp monitor. if the temp rapidly rises while under full throttle, go back to a larger main jet up 1 or 2 sizes.

on the shim idea, go to a shop that sells enthusiast r/c cars and look for some 3 mm ID washers and see if they sell them at varying thickness. that was one Idea I got while thinking about it. if they sell thin ones, you can buy a package with several in the pack and stack them if needed.

Yes Al we are still taking orders....send me a private message and we can get your order started

We get questions on how to box up my pipe ?

Instead of trying find a box that the pipe will fit in,

we have found that cutting up a card board box and wrapping the pipe securely in it works great.

Be sure to use the heavier cardboard and lots of tape also use double layers of cardboard on the ends for reinforcement.

Common sense will tell you where you need more tape or cardboard?




Here's a DT400 Sleeper Pipe on its way out !