Re: Hobbit engine+bike build/photo dump

Where did you buy those rubber clamps that hold your rad in place?

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

My original ramp plate guides gave up many miles ago so I've been playing with 3d printed ones out of pla. They last 40-50 miles. I ordered some pilot and main jets and got a few sets of the polini brand guides. A little bit of filing and they seem to be working. The bike will be in goshen indiana next week so I'm gonna rejet for the cooler weather. I don't want to blow up when doing the drag racing. So far the ignition system has been great. No hicups and nothing getting loose. I picked up a gopro session 5 to get some footage from now on. So far it has expensive tastes in memory cards to function properly.

Re: Hobbit engine+bike build/photo dump

tiiiight. need some clutch springs though, boiii.

you like that new gopro, I've been really considering getting the hero 5 with the karma grip

Re: Hobbit engine+bike build/photo dump

Totally normal JBOT /

Seems to be running good!

That pipe is holding you back though.

I knew you were running one just by the sound.

I have one as well but my hacked simo pipe is way better.

Maybe look into some really fast scooter pipes or hell,

Just make a custom one. It's not like you couldn't make a really kick ass one with your skills. (edited)

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

I brought the gopro with me to the goshen indiana rally. It worked out great, battery life is about 2 hours, about 4.5 hours of 1080p at 60fps on a 64gb card. First video is the "drag racing". I'm not sure of which pass it was, but I gps'd at 65mph. At an earlier rally I gps'd at 68mph down a slightly longer road. Rpms were hovering around 10,500 around those speeds.

Onboard video of my runs start at 9:30

Also is some of the rally ride video. lots of buggies.

More miles are on the bike and the ignition has been flawless. I took some good advise and looked at scooter pipes that are more or less made for my "mid race" cylinder. There seems to only be a handfull of good ones to choose from so I got this guy:

Its a Yasuni carrera 16, the unrestricted race version of the city16. Judging by what it acts like on other bikes it should boost my rpm range by a thousand or so. Without putting my bike on a dyno, I feel like my power comes on around 8,000 and pulls to 10,500 and thats about it. If I can raise that upper ceiling, I can get a good 75mph out of it without resorting to final drive gear changes and possible reduction of acceleration. I took advantage of the canada/usa exchange rate and got the pipe and complete topend gasket kit for $218. I'll update of course when I receive it. I'm sure there will be a couple good days left before the cold sets in to test it out.

Re: Hobbit engine+bike build/photo dump

Dave & Bummerzz Wrote:

-------------------------------------------------------

> tiiiight. need some clutch springs though, boiii.

Yea, I'm pretty sure you could figure out a way to custom machine your own precision clutch springs.

I just looked thru this first time in forever and caught the custom stator part. WTF! that's nutso. I feel like the only logical next step is some custom machined cases and even more lunatic scooter kits. and with all the custom crank possibilities that'd open why not stroke it out too?

Re: Hobbit engine+bike build/photo dump

NEAL SUMMERLIN /

Might as well build your own pipe. You done'n built the hell out of everything else. Let it rip , MAN .

Re: Hobbit engine+bike build/photo dump

yea 10.5 is all the h95 wants to do, i think if you added a rear bleed and shortend the h95 3 or 4 inches it would be a killer pipe.

Re: Hobbit engine+bike build/photo dump

I had Blake From Dos track me down a few Tecnigas Triops Race. Apparently they're the shit for low $

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

I received the pipe today. I'm very pleased with the quality of the pipe and hardware. The exhaust flange bolt spacing for some reason didn't fit with my cylinder. There wasn't enough meat to dremel them out so I made a new one. The h95 ID is 25mm, the yasuni is 27mm and fits the cylinder flange hole perfectly. I'm sure having a slight ridge at the port wasn't great for rpms.

I turned the old flange off the short header pipe and welded it onto the new flange:

Here's how it sits on the bike before changing the header angle:

And a side by side. It's a fair bit shorter, and much more volume. I'm excited to see how it goes.

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

I got the pipe cut and angled to fit the bike. I took a pic looking inside the pipe. Its understood that the yasuni city16 pipe, the "street legal" version has a few restrictions and an internal baffle to quiet it down. The carrera 16 is supposed to be the "race" version and doesn't have the restrictions. Well, they still put in the internal baffle. It covers the last two convergent cones. I'm hesitant to remove it based on the dyno sheets I've seen that presumably had them in there. I don't want to run the pipe then cut it, for the oily mess inside only makes the job harder.

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

Machined up a new exhaust hanger.

Re: Hobbit engine+bike build/photo dump

Would love some dimensions on those chamber sections...been studying pipe design

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

Here's the numbers I got. If you need a larger pic I can email it to you.

I got the internal baffle removed and finished the rest of the welding. I used mop'n glo to keep the rust at bay. I'm disappointed that it sounds exactly like the h95. About the same loudness too. Power under 8,000rpm is reduced and I will need to do some clutch tuning. Above that is a noticeable rise in power. I did not change the vario weights so the rpm is still 10.5-11k. However, it was trying very hard to get past 11k while accelerating. I'll play with the weights and see how high it will rev to. My issue, which is captured in the video, is what I think a fuel delivery issue. I hold wot for 8-10 seconds and the engine slows, sort of like a soft seize. I can let off the gas for some time and get back on it without any issue. I'm guessing my floatbowl is running dry. Its done it a handfull of times since I've had the water cooled kit, all when I'm doing about the same thing. In the video it happens at 3:14

Re: Hobbit engine+bike build/photo dump

ThNKS for the video Joe. Hobbits sound pretty much the same no matter the pipe lol. I got a VII Weak-Ends pipe it sound a'lot like your bike. I even got the same metallic rattle noise.

Does the slow down improve if you ever so slightly ease off the throttle? (still on main jet)

BTW, your bike has crazy acceleration power. I kept thinking "that bike would have no problems keeping up with traffic"

Re: Hobbit engine+bike build/photo dump

Can I ask a dumb question? I will anyway.

Have you considered using a small fuel pump to pressurize your fuel system? There are a few things to figure out. For example, in our gravity-fed machines, there is a float and needle to stop the flow of gas when the engine slows down, and a pump might force the float needle to stay open and overflow the carb. But might there be a way to turn the float into a switch?

OK, it might not be the best idea, but there have been a couple of threads talking about running the bowl dry at WOT. How do you compensate for that? Larger fuel lines?

TL:DR Nevermind, it might be too far off topic.

Re: Hobbit engine+bike build/photo dump

I've ran in to it before. You can run a vacuum operated fuel pump if you tap a port in the intake. Something like this works well:

https://www.amazon.com/dp/B00D7N8HRK/

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

What I tried first is tested the flow rates at the end of the fuel line and through the carb. There's some math that calculates how much fuel per hp per hour that an engine normally burns, and it seems like I'm about at that limit. My fuel line can flow 1.06 pounds per minute(ppm), while through the carb is 0.260 ppm. The stock vm20 needle seat hole measures 0.053". I increased the area of that hole 50% to a new diameter of 0.063". However, that only increased the flow rate by 14% to 0.298 ppm. I'll have to test it to see if it made any difference. I'll also play around with the main jet to see if there's any influence in that.

I modified the clutch to a higher stall. The previous setup was a stock clutch with malossi red springs. It engaged at 6,000rpm. I took jbot's advice and moved the clutch spring holes outward. I also lightened the clutch arms from 55 grams to 49.6 grams, about 11% drop. I kept the same red springs. By doing those two things it increased the stall to 8000 rpm. I don't want to rev much more than that.

I dropped the vario weights from 14.6 grams to 13.9 grams. It didn't seem to make much of a difference. It seems to stay at 11,000 rpm. I'll drop it more and see where the wall is at. If you can't read the numbers on the tach in the video, straight up is 7500.

Re: Hobbit engine+bike build/photo dump

Totally normal JBOT /

Yup.

Just gotta ride like you mean it with high stall springs.

Having a whole lotta launch up there requires constant vigilance.

Re: Hobbit engine+bike build/photo dump

hell yeah dude, now you're fucking cookin

Re: Hobbit engine+bike build/photo dump

that video should be added to jbot's page explaining the mod, "reasons you should do this to your clutch".

that thing is fasst

Re: Hobbit engine+bike build/photo dump

Well that's pretty depressing. It looks like an awesome pipe if it didn't have that internal baffle. I would love to see you recreate the pipe without the baffle and compare the two.

Did you do a video or anything on that tach? I would love to know more about who makes it, how it's wired, etc.

Joe Schuitema Wrote:

-------------------------------------------------------

> I got the pipe cut and angled to fit the bike. I

> took a pic looking inside the pipe. Its

> understood that the yasuni city16 pipe, the

> "street legal" version has a few restrictions and

> an internal baffle to quiet it down. The carrera

> 16 is supposed to be the "race" version and

> doesn't have the restrictions. Well, they still

> put in the internal baffle. It covers the last

> two convergent cones. I'm hesitant to remove it

> based on the dyno sheets I've seen that presumably

> had them in there. I don't want to run the pipe

> then cut it, for the oily mess inside only makes

> the job harder.

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

I did remove the internal baffle. I'm not sure how it would behave with it in there, we'll never know. The tach is a 16.6 hertz unit, so its matched to a single pickup off the crank. There's a crank position sensor(vr sensor) on the flywheel cover and a gm hei module to convert the sin wave to a square wave so the tach can read it. There's pics of the install a page or two back.

I couldn't put my foot down on the peg because of the silencer being in the way so I converted it to side bleed. I've got ideas of moving the pegs up further so that will help as well. I also shortened the silencer by 2 inches. I have no hard data to back it up, but it seemed to broaden the powerband. It dropped the initiall hit by 500 rpm and revved up a bit further. I did get it to lift the front wheel one time. I'll try some 60 foot times and get numbers.

Re: Hobbit engine+bike build/photo dump

Joe Schuitema /

Increasing the flow rate of the carb needle/seat didn't change the problem. It still started to bog/slow down after 5-10 seconds at wot. Richer jetting and retarding the timing a few degrees didn't change it either. I suspected it was an oring leak in the head that only occurred at high pressures. I changed the oring and took it for a ride today. Good news, it wasn't the oring.

The bog/slowdown I was feeling was the sparkplug getting superheated and lighting off the mixture early(pre-ignition). Keep in mind when I took the head off to change the oring, the spark plug and piston top looked perfect. I'll remember to put a cooler range plug in next time.

Re: Hobbit engine+bike build/photo dump

Downhill Harvey (OFMC) /

Ditch the CHT, and go EGT,

Re: Hobbit engine+bike build/photo dump

Totally normal JBOT /

You built a harder hitting pipe,

That can cause detonation at the same timings with a softer hitting pipe.

Re: Hobbit engine+bike build/photo dump

WOW first time seeing this...Very impressed

Re: Hobbit engine+bike build/photo dump

Dave & Bummerzz Wrote:

-------------------------------------------------------

> hell yeah dude, now you're fucking cookin

Re: Hobbit engine+bike build/photo dump

^merely pointing out Andy's unintentional joke... Love the thread, bike, AND the piston carnage. ;)

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account