Bike #5 1983 Yamaha IT175K

[95naSTA]

"You can buy cheaper, but you can't buy better for the price." I hear ya on this. You've got me thinking hard about this but it might not be in the bike budget this season.

After a hand full more hours of searching I finally figured out what front end I have. 1980-1984 Suzuki PE175. So I ordered that cable to try and get it to work.

I started with the lighting coil re-wind by measuring resistance and counting the coils as I unwound the stock coil.




I'm actually going to add a 50v (max) 10kuf cap to wire in-line with the half-waved DC to dampen the pulses and provide a mini-reserve. My LED headlight burnt out before the woods trip and I think the low rpm pulsing from the half wave rectifier made it unhappy.

[95naSTA]

So I'm getting pretty nerdy with this whole lighting coil thing. I really wasn't concerned with the lighting at first but this is kind of interesting.

With 12v bulbs I measured amps and voltage before and after the half wave rectifier for watts. 18-86 Watts AC from 1400-5k and 5-23 Watts DC. I measured RPM with an inductive gauge that now sits in the trip meter location. I started doing some calcs on what kind of Watt increase (AC) I could get with the new gauge wire at xx% more turns. Turns = volts and gauge = amps. At 30% more turns and 16% thicker gauge, I would get 27-130 Watts AC but still a low 7-40 Watts DC.

So then I started looking at full wave rectifiers.. I realized what while I'm rewinding the coil I could just make it a floating ground coil for the 2 AC leads to make one work. I'm going to try a cheaper 12v full wave rectifier/regulator I found on amazon with decent reviews.

I rewound the coil with 30% more coils and I tapered the winds up top in hopes they will clear the rotor. I decided to go with MG Chemicals Silicone Modified Conformal Coating to seal it all up. The resistance of the coil went from 0.5 to 0.7 Ohm with is roughly the same percentage of Wattage I'm hoping to gain pre-regulator ~40ish%. Fingers crossed it'll clear.





Last weekend I had no issues banging my plate off but I did break a plastic shock cover they don't make anymore. I repaired it with my plastic welder and some mesh.





Oh and using a PE cable and an IT speedometer didnt work.. it looked like it was working then it blew over and bent the needle..

[Sirius]

rewinding those magneto coils is impressive. I probably would have just bought a lithium battery kit and installed it on the bike to keep the light constant when the mag output is low when idling. 'Cause I'm just lazy.

[95naSTA]

I have a lot of patience for inanimate objects.. lol.

So that huge coil fit under the magnets without issue. But, it did not fit on the inside where the rotor slides over the crank. Lameee. I decided to hook up the full wave rectifier anyway. This involved floating the stock coil ground and running another wire for AC input #2. I took the same measurements as before but I'm now measuring amps through one of the two AC inputs to the rectifier. With this AC Amps went way up, AC Voltage when way down but did not equal out when you multiplied for Watts. DC Volts went up as expected but now it, along with AC volts seemed to plateau.



I rewound the coil again and the max number of winds I could get away with was down to 17.6% more with the 16% thicker gauge wire. After installing I measured again and it got a little more strange. Idle AC Amps and Voltage improved but they taper off sooner. DC Volts however were improved 0.5-1 across the RPM range.

In summary, electricity is strange, my full wave rectifier might not working completely correct and I went from 2.7 to 4.5 to 5.5 Volts DC at Idle. I would compare amps but I'm not sure how going from measuring from a single output coil to a dual output coil affects measuring amps. I would say I might have just been better off running the original 6V equipment with an AC regulator but the stock idle AC amps were very low to begin with.

Here's the data:


Also, I've been trying to get the bike to run better off idle by messing around with the pilot and needle clip position. It didn't seem to make much difference.. I was thinking it might be time to to the crank seals but decided to do a leak down test first. It turns out my base gasket is leaking:
https://www.youtube.com/watch?v=jQrvAMpJ8js

Good news is I have good compression:

[Sirius]

Replacing the base gasket should help things out!!

[95naSTA]

I got the base gasket swapped out and while I was in there I:

-Raised the exhaust port around 1mm
-Cut the exhaust pipe since it was crooked going to the head, removed roughly 15mm, welded back together square
-When up to a 330 main
-Cleaned the 30 years of grease and dirt off as best I could before I rattle canned the jug, head, pipe

The first few things I found in a Yamaha Tech Bulletin. The crooked exhaust was rigged with some Home Depot b.s. previously..

The low end (off idle) still has some hesitation but the midrange and especially the top end on this thing is wayyy better. The powerband used to be really tight and kind of fizzle out around 5-6k. Now it feels like I picked up at least another 1k rpm. It literally feels like I have another gear at speed. I'm going to wait to get that needle jet (in the mail) with the needle at the suggest clip height before I do anything else.

[Sirius]

Was there a little carbon on the piston?

[95naSTA]

Yep. I cleaned it when it was apart.

I swapped out the needle jet and took it out in the woods 2 weekends ago but I ended up getting a clogged pilot.. It was bogging pretty good down low and under load. I had no tools so I did some laps with the choke on. When I got home and took it apart, the pilot was visibly clogged. So that was easy.

My clutch is now slipping pretty good with some new found power and RPMs. What's crazy how good the bike feels cruising at 5-6k.. and getting on it from there.

I'll probably have it out a a couple more times this year just to hoon around on but it'll come apart for the clutch pack, polishing the tank back to the right color, some non-dry rotted tires and possibly the right front end.

[Sirius]

It's amazing how a clogged pilot jet will affect the way a bike runs. You'd think it would only affect the idle, but it crosses over into the entire bottom and lower mid-range.

You could try some different oil in your clutch as a temporary cure for the slipping (unless its too far gone). Certain oils, like Silkolene or Elf, tend to increase slippage, but also result in less drag when the clutch is disengaged. I don't know what you're using, but you might try a heavier weight or just a different brand. Not the aforementioned Silkolene, though!

If you're going to swap the front end, you might consider upgrading to a disc brake. I don't know if the bike came with disc or drum, but discs seem to perform better in wet conditions.

[95naSTA]

I ended up just going with the stock front end but I changed the seals/oil. It also got tires, a chain and gears.

Aesthetically, I cleaned up the plastics, had the tank polished, got a new front fender and slapped on some decals. It was cutting it pretty close but I was able to get it together before a weekend trip to Hilltop Lodge. This property is located in West PA, has 900 acres total, an older MX track that's on a huge hill, a circle track and tons of fun trails.









https://www.youtube.com/watch?v=aqrcr6ahFs4
That little twig where my front tire landed was where my back tire landed the last time.. But.. since I had already whiskey throttled to a bent bar scenario that morning, I dialed it back a hair.

Overall, I'm very happy with the bike. It rips for what it is. The only plans I have are to get taller bars with hand guards and some boots. I had intended to get some ADV style boots (as mentioned) for this trip but time flew by too fast.

[Sirius]

You got the old Yammie looking pretty good. Any get-off capable of bending bars is worthy of notice and tends to cool your jets a little. I've humbled myself so many times you'd think I'd be afraid to get on a tricycle, but memory of the last crash fades pretty quickly. Fortunately I've not been too seriously hurt during one of those crowd pleasers.

[95naSTA]

As per my last post I did end up getting taller bars and hand guards. I also got Alpinestars Tech 7 boots with an ADV sole. I was not pumped when I first tried riding with them on the street but it literally took me an hour to get used to them on the dirt and in the woods.

With the forks rebuilt, I realized the front springs weren't going to cut it. The front end was too soft and unpredictable. I picked up some race-tech springs based off their online calculator and it worked out awesome. The bike feels completely different.

I also found out that in addition to the forks, the bike had a PE175 carb. The mixing chamber cap cable guide had too much play for my liking and since I couldn't find one I just bought a used stock carb. Once I got the two side by side I noticed the mixing chamber was bigger on the carb that came on the bike. The OD on the inlet and outlet were the same at the new(used) IT carb but the outlet measured 36mm on the IT vs. 34mm on the PE carb. This is strange considering the IT carb is a VM34 and everything I read says it should be 34mm. Oh well, can't complain about getting a bigger carb when I didn't even mean to. I kept the jetting the same since it's the same as an IT200 and I doubt I'm flowing more than that. It feels good too.

I took the bike back to the property in west PA I mentioned in my last post and had even more fun. The bike felt awesome and I was definitely more comfortable on it. Now I can notice the chatter in the tires and ride in and out of traction in turns etc. I was also clearing the tabletop I got reality checked on last time consistently.

https://youtu.be/E0QWBm3OhM4

[Sirius]

It's amazing what a difference suspension tuning can make, even if it's merely changing a fork spring. I resprung the fork and shock on my trials bike recently and it has made the bike a bit more responsive. Not that the action wasn't ok before, but my fat a$$ was starting to overwhelm the springs a bit. Yeah, I could have dialed in some preload, but that's a poor substitute for the correct springs.

Bike sounds pretty good in the video, and I like the slo-mo over the jump.

[95naSTA]

Thanks!

[Sirius]

Actually your craft is pretty impressive for an 83/84 vintage machine.

[95naSTA]

What's wild is how dirtbikey it is but it's still plated.

I rode the bike back to back with my buddies '13 yz125 and it was lightyears better than mine. At 20 years I would expect it. But after working on the front suspension, I feel like the bike went from 50% to 75% there overall. Pretty sweet considering I can (legally) ride it on the street.

[Sirius]

I don't know what the requirements for tagging is where you are, but it shouldn't take much to get a bike road worthy in the legal sense. Lights, brake light switches, maybe a battery...but, yeah, being already street legal is quite a bonus.

I was going to tell you to stay off a new bike. Bikes made in the 80's can't compare to one made in this decade. While they kinda look the same, there have been subtle advances in suspension, engines, frame geometry, etc. My 2017 Beta trials bike is way better than my '04, which was way better than my '95, which was better than my 91, which was very much better than my '89. I'm not even going to mention my '79 Bultaco. It's just that my '17 is orders of magnitude better than my '89, and I loved the '89. If I still had the '89 and never rode anything else, I'd probably be fine with it (other than I can't get parts). But compared to the new bike the '89 is a tank. I'm not baggin' on your '83 nor calling it a tank, it seriously looks dang nice and it if runs and handles like it sounds it's got to be pretty sweet. It's just that if you really like the '83, you'd fall in love with a comparable 2019!

Are you running the stock rear shock on yours?

[95naSTA]

Oh, no doubt if I sprung for something newer, I would enjoy it even more. I'm just thrilled I can have as much fun on it as I am for the money I have into it. I sold my DT for $800 and bought this as a running bike for $500. I basically don't ride my DRZ anymore because of this thing.

I still have the stock rear shock unfortunately. I wouldn't be able to rebuild it in time for the next or last time I get the bike out this season and there might not be a next season for a while.

I'm sure I'll upgrade at some point but I'll need a spot with a garage out in Cali before that happens.

Getting stuff plated in PA is a PITA. Jersey is easier. I'm lucky my VIN is a dual purpose VIN. It was never sold as street legal in the US but was in NZ, AU, and UK with turns, horn, etc. The Vermont DMV I plated it through saw the type of VIN and didn't even question it. If it were off road only, I would actually have to get all the street legal equipment and have it inspected. I'm conveniently in the grey area.

[Sirius]

... there might not be a next season for a while.

Work gonna put a cramp in your riding time? A friend came by my house to ride his trials bike in my backyard (I have a bunch of rocks and a big-A log back there) and showed me the 2020 Husqvarna 300 he just bought. I was jealous.

[95naSTA]

That sounds like fun.

I'll probably be in Cali by next season and I'm not too sure if I'm only bringing the Ducati out or this one too. Part of that is not having a garage of my own in Cali.. yet. The other thing is the feasibility of having a 2-stroke street vehicle there. I'm not sure how either of those 2 factors will be addressed just yet.