DRP: Derbi Reactivation Project

[toratora]

That's correct I don't run a thermostat on kitted bikes, because they can fail, and produce a catastrophic event. I'm not getting this same warm up issue with the two other Stage6 kits, and I'm wondering if it's the head configuration. This is the older style Big Racing with the wacky metal head gasket. Later they introduced a newer head design that employs o-rings. I much prefer that setup. I can order a replacement head, and gasket kit, so I may eventually give that a try.

[kaldis12]

I had Barikit, Airsal, Polini kits, they needed a long time to warm up.

[jkv357]

Is everyone running without a thermostat?

I suppose they can fail, but I can't say I've had it happen.

[toratora]

I suppose if I didn't live in such a temperate location I might consider running one, and changing it regularly. Another reason to remove it though is better flow.

When I say a long time I mean a really long time. Like more than an hour of riding.

[jkv357]

I suppose if I didn't live in such a temperate location I might consider running one, and changing it regularly. Another reason to remove it though is better flow.

When I say a long time I mean a really long time. Like more than an hour of riding.

Do you have a thermostat to try?

I see a thermostat as providing a much more consistent engine temp. Getting up to operating temp quickly and staying there usually is usually better for the engine and should make more power. Temp changes would effect jetting as well.

I'll have to ask my race-engine builder friend what he thinks next time I see him.

[kaldis12]

Wow an entire hour of riding? WOOW That's really long. For me 10 mins at idle and max 10 mins of riding. I mean here its like 30 Celcius or more. I don't know, what's the temperature where you live?

[toratora]

J—I probably have one laying around. I've also been considering flipping the head around like on other kits, or even taking one of the heads from the 77 kits. I've just been so tied up with other things that I've not been able to really do any wrenching.

K—There's obviously something wrong with the bike!

[toratora]

Needed to go help out a friend today so I took the DRP. I really need to figure out what's going on with it. It could be ignition, but I think it's the jetting.

► Show Spoiler

[toratora]

I needed to go to the market to pickup some supplies so I thought why not swing by the park for some photos.

► Show Spoiler

[toratora]

Looking super clean. I'm scared of Chinese titanium fasteners. Usually if I'm choosing titanium it's for a critical application where high strength and light weight are paramount to keeping me alive. Not sure I trust anyone who sells on aliexpress to that level.

Nearly all the fasteners on the bike were replaced. Most of them are stainless, which were purchased from the Bolt Depot. I did get some things from Derbi via EasyParts, such as the axels, and spindles. The few titanium bolts that were sourced for the bike went into basically noncritical locations—which is to say engine case bolts. The bolts appeared to be a decent quality. They were amazingly light. I torqued each one with a torque wrench, and had no issues. The cases aren't leaking, and I did perform an air leak test on the engine—which it passed swimmingly.

But I wasn't brave enough to order bolts for anything that would take a load like suspension, brakes, frame, etc. Most people when they source titanium fasteners they employ them in rotational, or unsprung areas where they can provide the most benefit. Obviously that's not what I did here. Basically it was an experiment which worked out well enough.