Going for broke 2, the bridgening

This DR kit, through fucky experimental porting got snag city, but everything else was cool, so I brazed in a bridge awhile back cut from a DR fin (with relief so it wouldn't bow out once hot)

It ran good but never great, but I thought the giant ex would rule.

Ended up I left the bridge way too long inside the port, and didn't carve enough out in the ports tube.

So basically the exhaust port was cool, but the ex tube restricted it.

So im going for broke again.

Timing is legit on this one tho, (round 22mm), don't need to go crazy with timing to make big power with 65cc.

Popped thru the wall again cuz DR has a simliar casting to the stock Jug.

Yeah, so ready to go, just waiting on the jb to dry on the cases so I can match them to my DR derestricted transfers.

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(edited)

Re: Going for broke 2, the bridgening

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Re: Going for broke 2, the bridgening

Trying something I saw in the internets.

I read that having a bit of flat lip on the cyl junction into the pipe can help with a nozzle style effect on the exhaust. I didn't add it to top and bottom, as the bottom had the lip and I just decided to leave it for now. If I like it I'll add a flat braze lip to the top too.

I'm going for broke again

And this time I'm pissed

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Re: Going for broke 2, the bridgening

Ľ̷̝̽͒i̶̛̼͑͠ȁ̸̧̛̽m̵̻̟̯̀̅ ̷͎̙̽̊F̶̲̺͑̓ F /

The abridged version

Re: Going for broke 2, the bridgening

Ok that's good

Re: Going for broke 2, the bridgening

I'm scared. Those little holes at the bridge could trap hot gasses and make a big mess of metal out of all your work.

But without experimentation, we'd never have the atomic bomb.

Re: Going for broke 2, the bridgening

Lol

You're a pussy

Re: Going for broke 2, the bridgening

Lol(edited)

Re: Going for broke 2, the bridgening

Lol 2, the worried mopedder

Re: Going for broke 2, the bridgening

> JBOT Admin Wrote:

> -------------------------------------------------------

> Trying something I saw in the internets.

>

> I read that having a bit of flat lip on the cyl junction into the pipe

> can help with a nozzle style effect on the exhaust. I didn't add it to

> top and bottom, as the bottom had the lip and I just decided to leave it

> for now. If I like it I'll add a flat braze lip to the top too.

>

> I'm going for broke again

>

> And this time I'm pissed

The cylinder I just got for a future engine has the flat top and bottom outlet on the exhaust port. The boosters also have partial ducts that extend to the outlet.

The technical sheet also mentions altering it will decrease performance.

Re: Going for broke 2, the bridgening

Interesting. I wish all those people talking of "port matching" woulda mentioned this

Re: Going for broke 2, the bridgening

Maybe I'll add braze on top tomorrow before I clean up and install them

Re: Going for broke 2, the bridgening

Barack Obama /

You should widen the fuck out of the exhaust & make an adapter plate for a bigger header

Re: Going for broke 2, the bridgening

Go away

Re: Going for broke 2, the bridgening

Barack Obama /

> JBOT Admin Wrote:

> -------------------------------------------------------

> Go away

Haha

Re: Going for broke 2, the bridgening

how does the brazing like oil soaked metal?

Re: Going for broke 2, the bridgening

> JBOT Admin Wrote:

> -------------------------------------------------------

> Lol

>

> You're a pussy

Maybe, but I won't be the pushing a bike home with a brass imbedded piston that looks like a rapper's grill.

Re: Going for broke 2, the bridgening

See, you're scared cuz you don't understand the science.

It's bronze, Einstein

It runs with this bridge, it has run for hours and hours.

I'm just doing more porting.

If you're afraid to fail you will always fail

baird co Wrote:

> -------------------------------------------------------

> > JBOT Admin Wrote:

>

> > -------------------------------------------------------

>

> > Lol

>

> >

>

> > You're a pussy

>

> Maybe, but I won't be the pushing a bike home with a brass imbedded

> piston that looks like a rapper's grill.

Re: Going for broke 2, the bridgening

Doesn't give a shit, I'm getting the cast iron cherry red, no oil can survive that.

> Yung Spil Wrote:

> -------------------------------------------------------

> how does the brazing like oil soaked metal?

Re: Going for broke 2, the bridgening

Ľ̷̝̽͒i̶̛̼͑͠ȁ̸̧̛̽m̵̻̟̯̀̅ ̷͎̙̽̊F̶̲̺͑̓ F /

Don't you want the exhaust outlet to be about 75% of the surface area of the exhaust port? or is that just something I heard

Re: Going for broke 2, the bridgening

> Ľ̷̝̽͒i̶̛̼͑͠ȁ̸̧̛̽m̵̻̟̯̀̅ ̷͎̙̽̊F̶̲̺͑̓ F Wrote:

> -------------------------------------------------------

> Don't you want the exhaust outlet to be about 75% of the surface area of

> the exhaust port? or is that just something I heard

Never heard that before .

Maybe you're confusing that with the port area to cylinder measurement ?

Re: Going for broke 2, the bridgening

You can't run an exhaust main port that's over 65-70% of bore without some form of ring support or very oval shape or you'll beat up the ring or snag.

You can widen an exhaust half way the way across the cyl, to the mid line above the transfers. Done it many times and the power is nuts

But as to the ports outlet yeah, I had this one ver restricted before.

Probably getting close now to optimal sizing(edited)

Re: Going for broke 2, the bridgening

Was doing more bridge cutting and low and behold I saw another hole on the other side of the bridge.

I did this thing so long ago I must have not fit the chopped fin too well.

Well then I checked to see if the hole went all the way thru!

Well shit it did.. haha

So I tried something.

Tried to use it as a lil baby port.

But no luck. Wouldn't run because the piston oiling holes passed right over the hole, basically killing all case vacuum. Nbd

I also added that nozzle output, and cut the cases and filed flat.

This is how you file flat, masking tape over one side of file and none on the other. Easy Peezy

So then I realized I'd have to re braze the bridge again to seal that hole. Oh well.

So then I did that and today I'll smooth it and see if it'll run again.

I also added bronze on the bridge itself to see how it wears. I had put a bit too much relief in the original bridge, it'll be cool to see if the bronze holds up. Or if it doesn't hold up. Nice to know things based on fact and not lil baby fearful myths.

If I can kill this kit today, then I can move on to throwing an insane wc kit I have onto this bike. No skill or challenge required but ripping is fun.

Back to it!

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Re: Going for broke 2, the bridgening

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Re: Going for broke 2, the bridgening

Hey man. Cool work.

You can also file flat by draw filing. I like doing it with a 2nd cut file for maximum finish. The more surface area the file comes in contact with the less it will cut other than the high spots. You can draw file stuff dead flat. It's a really simple technique

If you tape one side you will still get a little bit of a taper.

I can't really tell if you are filing the bridge flat or relieving it a few thou but it should be relieved as it will heat up faster than anything else.

This is probably the most exciting thread on MA right now.

Re: Going for broke 2, the bridgening

You can't draw file correctly with the crank in the cases, don't have any to remove any material from the other side. not concerned about a masking tape thickness taper. It'll seal great.

Done it many times.

The bridge formerly had a bit too much relief, so I added bronze over it. Will still add some relief but not as much. And the bronze being less hard than the cast, the ring will make it's own relief over time down to the cast below. Don't mind using a ring as a tool for a bit, then I'll replace said ring once everything is broken in.

Fuck it I'm just experimenting.

Some experiments work, some don't. The trick is to remove ego from the equation, that's the way to learn and generate wisdom.

It's been so long since I've really dove into 2 stroke experiments. The feeling of total focus and watching the results of unusual experiments is thrilling like nothing else

Re: Going for broke 2, the bridgening

> JBOT Admin Wrote:

> -------------------------------------------------------

>The feeling of total focus and watching the results of unusual experiments

> is thrilling like nothing else .

And , the lift you get when it works can not be denied . :)

Re: Going for broke 2, the bridgening

♣Slew Foot♣ /

Remember brass expands higher than iron.. nickel iron rods and preheat.

Awesomeness you should have a Mic on the maiden ripp I wanna hear that scream.

Its like plugging your guitar right to the wall outlet...

Freaking poetry my man it deserved a haiku .

Re: Going for broke 2, the bridgening

If you're going to waste the bronze, you gotta do it big!

Re: Going for broke 2, the bridgening

Barack Obama /

Should of bought the stage 6 kit

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