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DRP: Derbi Reactivation Project

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toratora
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Derbi Reactivation Project: Bidalot Disappointment

Post by toratora » Mon Aug 12, 2019 12:39 am

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I started off making some decent progress installing the Bidalot RF70WR kit today, but I ran into two gotchas. The first one I was able to overcome with some hand tools, but the second one was beyond my local resources.


When fitting a kit there are some basics, like sussing out the squish, checking the ring gap, etc. To check the squish you have to clean things up, select a base gasket, fit the piston onto the rod with the little end bearing, slide on the cylinder, attach the head, and then take a measurement. Easy right? Well it is suppose to be easy.

A note with these photos. The last kit I installed on this engine was one of the Stage6 BR77s. The cases were slightly modified to match, and as can be seen here the Bidalot can accept an even wider transfer. Since the flow is up into the cylinder I was planing on leaving this as it is—which I still might do. There won't be any obstruction of the charge going into the cylinder, but there will be a slight reduction of through put.


The ring gap checked out okay at .2mm, but the wrist pin would not fit. It turned out to be that the piston was such that the bearing did not fit the piston. I was able to deal with this with some carful attention from a hand file, and some sand paper.


Next up was checking the squish, but that wasn’t going to happen tonight due to a complete lack of studliness.


Replacement cylinder studs are illustrated with the advertising for this kit. However, none came with this kit. I figured that on the Euro2 they must not be necessary. Turns out that’s not the case at all. The stock studs are way too short. You can get the head nuts started, but they cannot be torqued even enough to check the squish.


Another issue with the RF70WR is the placement of the head to cylinder attachment bolts. One is placed squarely in the center of the heads water outlet. I kid you not. Imagine losing the washer is this diminutive aluminum maze!


In happier news the paint matched up fairly well. Since it will be a while before I get some proper engine studs the paint should have plenty of time to cure. :paw_prints:
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toratora
Posts: 2932
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
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Derbi Reactivation Project: Studly

Post by toratora » Fri Aug 16, 2019 9:39 am

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I finally had a moment to remove the stock studs in order to get a measure on them. Had to employ the heat gun to loosen them up. Once out I measured them. They are longer than I expected coming in at about 120mm. The studs that came with the newer ProRace kit were 125mm. The silver one in the photo I got from Maxiscoot when I got the BRK kit. At 115.5mm proved to be too short for that project, and again with this one. I might be able to get away with 125mm studs for the RF70WR, but it might be better to get something a bit longer. Maybe even go with 130mm. I will have to check out what Treats has in stock. :paw_prints:



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