What would it take?

chancer · Dec 3, 2015

"definatley "

Flyinhillbilly · Dec 7, 2015

Me and my neighbor ported the head Saturday night and reassembled it with all the same parts ( yes, we re used the head gasket) kind of an experiment to see what we could get out of port work alone. It sounds different, and idles a little slower (lower port velocity at low rpm is my guess there) but there was no improvement in top speed which leads me to believe that my valve springs are wasted, but I have some new ones coming with the new cam. I also discovered that this has a dish piston in it that I may save for the supercharged version of this engine (future plans include positive manifold pressure and a mix of nitromethane and methanol in the fuel tank) but I think I'm going to order a flat top tonight. We also back cut the valves, they had a pretty sharp lip on the backside right before the seat area, so we smoothed that out as well. We have access to a valve machine, but we did it with a hand drill and a dremel to keep it DIY. We got some video and pics that I'll get posted within the next couple of days, and my parts should be here any day.

---------- Post added at 10:32 AM ---------- Previous post was at 10:09 AM ----------

Here's a video with my initial impression of this head.
http://youtu.be/OIKVZQ-BUbg

Poboy kartman · Dec 7, 2015

Did you do anything...(or plan to)...to address valve shrouding? Looks like you have a little room for improvement there....

As far as the rest...well..... :popcorn:

Flyinhillbilly · Dec 7, 2015

Yes, already done. I blended the "eyebrows" into the cc. As far as the rest of it goes, grab your popcorn, this could get good. This is just something I'm fiddling around with, just a fun little pit bike. I have a turbo race car that wears me out trying to get everything juuuuuust right, so this is a great stress reliever. I'm sure I'll blow it up a dozen times, but that's part of what makes it fun. The battle cry for this project has became "we ain't building a Stradivarius".

Poboy kartman · Dec 7, 2015

Cool....one other thing that may help you to know....(if you don't) ...is that you can lap in the flywheel and do away with the key ....allowing you to fine tune the timing.

Flyinhillbilly · Dec 7, 2015

I read about that, this is my first attempt at souping up one of these, all my experience is with cars and multi cyl bikes. I really have no idea what I'm doing, but that was the case when I started fooling with cars too. I'm very appreciative of all the advice, and I'm sure I'll need lots more of it.

Flyinhillbilly · Dec 7, 2015

Parts came in today from BSP. I ordered a flat top for it this afternoon, so I'm going to wait until I have that in hand so I can do all of the mods at once.

Flyinhillbilly · Dec 14, 2015

Well, the flat top came in, turns out it wasn't a flat top. The picture was, and it didn't say different in the ad, but it's a bigger dish than the piston in it. I decided to go ahead and put all the parts in it, and what a difference. It actually pulls on your arms on midrange and top end. The carb still needs lots of tuning, but I'll probably piddle with that this weekend some. I got it close enough to get it out in the street and wring it out a few times, and even out of tune it's noticeably stronger everywhere. I'm actually surprised it picked up as much power as it did. The torque converter will be the next upgrade, if it gives me about the same percentage of improvement as these parts did, I'll be happy as a pig in poop.

Poboy kartman · Dec 14, 2015

Yeah....I foresee a sty keeper in your future!!!!! :roflol:

Get ready for the fun! :popcorn:

Flyinhillbilly · Dec 15, 2015

Ok, dumb question time.

Does anyone sell an adjustable coil braket for the GX160? I searched but couldn't find one which doesn't really surprise me since my Google fu blows. Also, will the Methanol conversion kit for the GX200 carb fit my BSP race ready carb?

OzFab · Dec 16, 2015

Dang, I wish I'd seen this thread earlier, I would've suggested a GX140 head; it has a smaller (14cc) combustion chamber than the 160 head... too little too late...

Flyinhillbilly · Dec 17, 2015

Fabroman said:
Dang, I wish I'd seen this thread earlier, I would've suggested a GX140 head; it has a smaller (14cc) combustion chamber than the 160 head... too little too late...

Not really, I think I'm going to put a GX200 crank in it, and do some more with the head. If a 140 head will help me make more power then I think that's what I want to do. I'm very happy with the return on investment modification wise so far, so more is betterer right? This thing needs to be able to physically harm a 250lb biker ( my neighbor wheelied it over backwards and cracked his tailbone, so we're getting closer.)

(Edit) any idea how many rpm a 160 rod will take before it gives it up?

chancer · Dec 17, 2015

At least we know you guys are Big bad Bikers, messing with this thing. This thread is sooo different than so many others that harp on safety of Children. Here we are trying to help you make a ride that will "Physically harm a 250lb biker".
Carry on

Poboy kartman · Dec 17, 2015

Well....no one wants to see the children get hurt....

Now....a 250 lb. biker....hmmmmm.....I might pay to see it ....or DO IT!

Just kidding guys...I've spent a lot of time hanging out with bikers!

EDIT: Last bunch I ran across had the coolest handle ever....'Skeleton Crew'.... naturally with a skull incorporated....didn't catch where they hailed from, but we had a blast chuggin brews and tossin horseshoes!

OzFab · Dec 17, 2015

Flyinhillbilly said:
Not really, I think I'm going to put a GX200 crank in it

Be aware that the GX200 stroke is 9mm longer than the GX160, which means you will need a shorter conrod or piston...

Flyinhillbilly said:
If a 140 head will help me make more power then I think that's what I want to do.

IIRC, a 160 head is 18cc vs the 140s 14cc head, meaning a higher compression ratio; I would suggest recutting the valve seats to fit the larger 160 valves;

However, if you intend to stroke the engine, this may not be a good idea without a billet conrod... the compression ratio will end up through the roof...

Flyinhillbilly said:
any idea how many rpm a 160 rod will take before it gives it up?

Usually somewhere around 5500-6000rpm...

Flyinhillbilly · Dec 17, 2015

Lol, I love my biker buddies, you guys will too once you see the videos. Here is a video of it idling, and one of me doing wheelies in my neighbors shop. I have got the carb pretty close, but it still needs some work. I think that will all happen Sunday probably.
http://youtu.be/ftCdrlPHBE4
http://youtu.be/pQzoHKvbMpA

---------- Post added at 09:01 PM ---------- Previous post was at 08:59 PM ----------

Fabroman said:
Be aware that the GX200 stroke is 9mm longer than the GX160, which means you will need a shorter conrod or piston...

IIRC, a 160 head is 18cc vs the 140s 14cc head, meaning a higher compression ratio; I would suggest recutting the valve seats to fit the larger 160 valves;

However, if you intend to stroke the engine, this may not be a good idea without a billet conrod... the compression ratio will end up through the roof...

Usually somewhere around 5500-6000rpm...

Thank you. I think what I'm going to try to do is leave the piston out of the bore and set my cyl head to piston clearance through a combination of head gasket thickness and milling the piston. I'm kind of getting into seeing what I can do with factory parts.

(Edit) when I say biker, I'm not trying to imply that we're a bunch of big bad dudes. These guys are probably the realest buch of guys I've ever met. Just fun loving, good dudes. The biker thing is me trying to say that these guys are well versed in operating two wheeled machines, so this needs to be extra stoopid.

Flyinhillbilly · Dec 19, 2015

Well we drilled it out so that it would fit, and with a little bit of help from an A dapter kit, we had that engine runnin' just like a song.
http://youtu.be/eLROIAhWbA4

---------- Post added at 01:45 PM ---------- Previous post was at 01:09 PM ----------

Flyby on 15% nitro
http://youtu.be/F4cM9UiN16c

2SlickNick · Dec 19, 2015

With those upgrades and the stock gear ratio, sure makes a wheelie machine.
I foresee a lot of sore tail bones and a few head traumas surronding that bike. Lol.

Flyinhillbilly · Dec 19, 2015

You're most likely right

http://youtu.be/k_bMzktE2QQ
Dragged my neighbors sons pw80 and my other neighbors honda 350. I need to out a fuel pump in it because it's consuming so much fuel tha it is emptying the fuel bowl. I have the 15% tune pretty well nailed down, and as soon as I finsh that gallon I'm stepping it up to 30%. Torque converter is the next step. I really appreciate all the help you guys. This thing is really starting to wail.

(Edit) 42 mph according to gps.

http://youtu.be/XwBNyQQInow

minibiker · Dec 20, 2015

I think just the tav woud make a wheelie machine . I have a baja mini bike with a tav and stockish predator and that thing will wheelie with me no problem and scares the crap out of my fatter buddies I weigh 240 lbs. Hi rpms and tavs don't mix they start to slip after a while. I have a racing clutch on my high rpm predator .

What would it take?

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