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PPMPR: Project Poor Man’s Pro Race

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toratora
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Replica: Derbi GPR
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Project Poor Man’s Pro Race: Doc Wong’s Rider Clinic

Post by toratora » Mon Jun 24, 2019 9:39 am

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Doc holds these awesome ride clinics once per month through the Santa Cruze mountains. He provides a one hour lecture in his office, and then leads a ride that usually takes about five hours or so, depending on lunch, and route deviations. I took the ProRace out there for a thorough testing of the build. I found that the old ProRace kit isn't running too great. There just isn’t enough bottom end to make it a viable ride. Off the pipe the bike is very difficult to get moving. On the pipe it is quite nice, but to keep it there you must ride in Demon Mode :smiling_imp: the entire time, and that can be more than a little difficult!!


I rode down to Doc’s with Jeff. He was on his RC390, which had no problem outpacing my bike. GX was suppose to ride with us, but he failed—something about a breakfast. He did catch up to us down in Belmont. Doc’s rides usually separate into a few groups—group one is for very competent riders that know the roads. Two is for competent riders that want to take it a bit slower. Three is for newer riders, and this time we had four groups. Group four was a ladies group. Usually I ride in John’s group two when he’s there. When I go on the 899, and John isn’t around I’ll volunteer to lead group two. On the Derbi I don’t have enough power to lead a group, but I can ride in group two—mostly because John is very accommodating to my special needs. Jeff and GX elected to ride in group one.


Doc’s office is located in a shopping center in Belmont. I parked my bike right at the front of his place since there was an opening large enough for the Derbi, with a nice piece of shade. During the lecture a little girl walked by the many bikes followed by her father. She walked right up to the GPR, reached up to put her little hand on the pillion seat and then placed her nose right up to the bike at which point she said something to the effect “Daddy it smells good.” His reaction was to pick her up, and walk away. The two stroke aura still reaches out to even young children. Praise Be. :motorcycle2: :dash: :dash: During this time I was fumbling to get the phone out, place it in camera mode, and snap a shot, but I was far too slow.


On the long straights, inclines, and such I had a very difficult time keeping up with the pack. Even starting out would often result in being passed by a number of riders. The power band on the bike is so skinny that frequently the Rs are lost when shifting from one gear to the next, and you end up off the pipe back in waaaaassss vile. So shifting must occur just at the end of the over rev. Without a working tach this proved to be a little more difficult, but I started to get the feel for it.


In the corners it was required to stay on the pipe in order to have power to come out into the straights. Usually this meant being in third gear, and making sure the engine was running at 10K or more. This had the effect that in anything with tight corners allowed me to basically run away from the group. Gazos, Swanton, Stage, 236 were all examples of the bike being able to out perform much larger bikes that should have blown away the Derbi. Even on parts of Empire I found I could go deeper into the corners well beyond where the bigger bikes were braking. It’s kind of fun to pass an R6 and a GSXR at the same time into a corner going up hill!! :jollyroger:


Once again on 236 the GPR reigned supreme. I’m sure if I was in group one with the RC390s I would have had some serious competition, but in group two I was way ahead of everyone.


But it wasn’t all smiles. Once again on Jamison the front brake went out. Similar to what’s been happening on the bay side of Bo-Fax. Every time I ride Jamison lately the front completely goes out. It comes back with some pumping, and once it cools off it is fine, but for a bit there’s entirely no front brake. :scream_cat:


As is usual on Doc’s ride we lunched in Davenport. I went to the combini, and got a grilled cheese with onions and avocado. It was quite yummy. Most folks go to the Mexican restaurant, but for me the lines are too long, and the price is too high. The food is generally quite good, but a budget is a budget, and it must be obeyed! I would like it if we would sometimes lunch in Bolder Creek. The Red Pearl has some tasty vegetarian fair that I truly enjoy.


Doc’s ride tends to wrap up at Four Corners where Doc hosts a short post mortem, and people hang out a bit. Jeff had to get back to SF, and GX wanted to go off with the R6 and GSXer riders. I needed to head up to STP for gas. When I got there Joker Rio and his gang of wily SuperMoto terrorists were hanging out. Since I was a fellow two stroke rider I was invited to visit. It was quite a nice round of bench racing since every one of them is an avid two stroke lover. The new tables and benches set up next to the Hydrogen station make for a nice community center.

Then it was up 35 to 92. The section from just a bit north of Kings/Tunitus was freshly paved all the way to 92, which made for a pleasant ride. When I finally got home I was quite exhausted. The GPR ran well within its limitations. Still I think I’m going to have to figure out how to get more low end out of the engine. It is fun riding in Demon Mode :smiling_imp: , but it would be nice to have a chance to ride a little bit softer from time to time. :paw_prints:
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jkv357
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Re: PPMPR: Project Poor Man’s Pro Race

Post by jkv357 » Tue Jun 25, 2019 6:19 am

Sounds like a fun time!

Do you think the poor low-end/extreme high-end power is coming from the port timing, pipe, a combination, or something else?
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toratora
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Project Poor Man’s Pro Race: The Brembo

Post by toratora » Tue Jun 25, 2019 1:39 pm


I had a moment to snap a few shots of the Brembo caliper in relation to the Derbi. These are just some rough shots to provide some idea on how to go about finding a proper solution. This is with the stock 260mm disc rather than the 300mm, but it still provides some context. :paw_prints:

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Berkeley
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Re: PPMPR: Project Poor Man’s Pro Race

Post by Berkeley » Tue Jun 25, 2019 11:55 pm

The ride and the bike look awesome!
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toratora
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Project Poor Man’s Pro Race: Responsive Design

Post by toratora » Sat Jun 29, 2019 9:39 pm

jkv357 wrote:
Tue Jun 25, 2019 6:19 am
Sounds like a fun time!

Do you think the poor low-end/extreme high-end power is coming from the port timing, pipe, a combination, or something else?
Yeah I highly recommend Doc’s rides. I do organize Replica rides down there too, but most folks can’t handle a 200 mile day on these bikes. Which is such a shame since it is oh so worth it!! :shock:

I really don’t know why there is no bottom end on this kit. It is running strong on the top end. The thing is this kit, the pipe, and the carb were designed to be on the race track, and it would then be wide open most of the time. So it could be in Demon Mode :smiling_imp: by design.
Berkeley wrote:
Tue Jun 25, 2019 11:55 pm
The ride and the bike look awesome!
Thanks. It is a whole lot of fun to ride this bike. If you get one of these older models you’ll be surprised how much quicker they turn than the current brood. :paw_prints:
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toratora
Posts: 3161
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Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
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Project Poor Man’s Pro Race: DC DC

Post by toratora » Sun Jun 30, 2019 12:39 am


The MyChron3 dash runs on 7.5 volts. The bike produces roughly around 12 volts. In order to get the MyChron3 working properly a DC to DC converter must be employed. When I got the MyCron it came with a DC to DC converter, and harness, but the converter seems to have failed as it was only outputting 2.5 volts. I was able to find a replacement on Amazon.

I also inserted a switch in front of the converter so that it doesn’t have access to the battery unless it is authorized. I suppose I could have been more clever about this like Berkeley and wired it through the key switch, but I actually wanted to have a button so that I could disable the circuit independently.


The old CPT converter was a little bit nicer with an aluminum box. The new Knacro converter is all plastic, but both of them had pretty much the same stats, wiring, and features making the switch quite simple. The CPT has a higher wattage rating, so I’ll want to keep an eye on the Knacro (22.5W vs 15W). Still they are both rated at 3A so things should be fine.


Then it was time to cut off the old shrink wrap, and disassemble the old harness. After which tin up the ends of all the wires. The switch use to come with connectors, but no longer. In this case it didn’t matter as I was going to be installing the switch inline before the Knacro.


With all the wires tinned up it was easy to assemble the harness. Unfortunately I was all out of shrink wrap, so I had to get out the black tape and wrap it the old fashion way!! :?



Once assembled I did a quick test, and huzzah!! it worked!! :ghost: I was very concerned that it might have toasted the Mycron.


Then I installed it properly, and amazingly it still worked! After this I buttoned up the inner fairing, and noticed that the throttle cable was binding when turning the bars to the right. I had to re-lace the cable to get it to function properly.


On the Doc Wong ride the cheap, but very expensive Airtech fender broke. I didn’t have time, nor the resources to fix it, so I Macgyvered it together with zip ties and black tape. Not the proper way to go about it, but good enough for now. It is wrapped around the reflector so that should provide fairly decent support. When I fix it properly I intend to glass in some metal support (which it should have had from Airtech).


After all that it was time for a test ride!! :heart_eyes_cat: I took it on my usual route of late, which brought be near the Chipotle, and I also visited the Target for some beverages. The bike was much more manageable to ride with the tach, and it was interesting to see where things were. It’s getting on the pipe at a bit over 9K, which is lower than I thought, but still fairly high since the bike really won’t move if it is not on the pipe! :scream_cat: At six, seven, even eight K it is total Boggsville, and it pisses off the cars behind me. So it’s very much a case of screaming off the line everywhere. :paw_prints:
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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
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x 1977
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Project Poor Man’s Pro Race: Sunday Ride

Post by toratora » Mon Jul 01, 2019 9:39 am


Sunday I rode over to Jeff’s shop to entice him into going to the D-Store to watch the Assen GP race. He was torn, but the opportunity for a little :smiling_imp: Demon Adventure won him over. After the race we had a fun ride back to his shop, and then I went to the Taco Bell for some Potato Tacos. :paw_prints:
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User avatar
toratora
Posts: 3161
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Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
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Project Poor Man’s Pro Race: Romping around the City Two Stroke Style

Post by toratora » Tue Jul 16, 2019 11:39 pm

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Had to run some errands which provided me the opportunity to go and ride the ProRace bike. One of the stops was to see Catherine over at the Daly City Tool Mart.


I also visited Kent’t place. Those of you that are FLCL fans will recognize Haruko’s scooter! He also had an obscure Chinese race bike magazine from the previous decade. I was thumbing through it, and there was Youichi Ui! How cool is that!! :ghost:


A couple more locations graced with the presence of the two stroke love. :paw_prints:
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User avatar
toratora
Posts: 3161
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Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
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Project Poor Man’s Pro Race: Time in the City

Post by toratora » Thu Jul 18, 2019 9:39 pm

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The ProRace is getting a bit of City action recently. I went downtown on it today, and then rode home through upper Market, and down O’Shaughnessy.At the top of upper market there was some construction going on. One of the workers ran over to me while I waited at the light and asked what size the bike was. I responded 50. He looked at me dumbfounded, and said 50 about four times. :dizzy_face: Then he ran back and told his buddies—they were impressed. When the light went green I lit the engine up to around 11K before letting the clutch out, and also slipped it a bit going into second to keep it in the Rs. When you do that the bike hauls ass. Demon mode desu. :smiling_imp:

I really want to get the engine such that it is able to be ridden in not Demon mode too. It is tiring to ride at 100% all the time.


The older GPR is just such an awesome chassis. It is really amazing that twenty years later that in this class you can’t actually buy a better bike. :paw_prints:
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