Cynic

Seems odd for the choke, I'm only looking at drawings. The daughters is manual choke. The RX my daughter has is the AM6 engine, better or worse than the derbi is down to personal preference I think. The Aprilia forums certainly suggest as much. http://www.apriliaforum.com/forums/forum.php Seriously this is the forum for these bikes, it is very active, mostly American but not exclusive and replies come pretty quick.

So that's a Derbi engine not the AM6? Looking at the (limited)info I have for the RX after rebuilding my daughters the choke is pulled on by the cable, from that I would say that the choke will be on with the plunger fully pulled up.

This may sound odd but it would not be the first piece of test kit to go south. Have you tried the compression tester on your DT.

Depends, what year is the rx.

Ok, first and most important bit. Stating everything is perfect is wrong and not helpful. First thing that springs to mind is the reeds, if they are not sealing properly you will have issues. Also the exhaust, is that clear, a 2stroke pulls air back from the exhaust during the cycle, if that is badly restricted or blocked by a build up of crap (on my daughters bike the 20mm pipe on the exhaust was so choked a pencil wouldn't fit) it will reduce the draw.

Oh I know that, its just the fact it was counting up when he turned the ig on. He was expecting a static figure. Works well though and matches my sat nav so if anybody needs an accurate speed check.....

Hmm, and in other news. The TDR passed the MOT with flying colours, complemented on the wheels too. The spedo threw him a bit of a curve as he had to wait 30 seconds to see the mileage while it calibrates. Rides really nice on them too, got a bit of a weave at 90 but I think that is the suspension being a bit hard. Had the same thing when I first got the bike.

Well done. You really will have done as good a job as a 'professional'. Your not thinking about a dozen other things, your doing something you want to do. The professional is being paid. They will never dot the i's and cross the tee's like you will. Have some faith in yourself and enjoy the money you saved, your looking at 60-70quid an hour these days with a minimum fee.

Just put a meter on it. The connections will be behind the headlight.

Yep, nothing behind it, well shouldn't be except the mag and the sprocket that is. There will be a gasket and you could on an old bike find fuel in there with a bad crank seal.

No I didn't. Have to admit I skipped ahead. Just rattles me with all of these you tubers. Yes some help but many don't give any real information. All he did was plug in the resistors sold by the people who make the indicators. I was expecting more I suppose, certainly not woodscrews. Could have at least used pan heads. Plus if you have a bike with a single idiot light for the indicators you still need 4 and with the rating on those resistors you have doubled the load on the indicator circuit.

Yep no fuel pumps or faf with these although you should, if the battery is charged hear the powervalve self clean. You can hear the servo do its thing. I was just making sure on the kill switch. Check it works with a tester so you can trust it (no spark could be ANYTHING). As far as starting goes. If its a stock motor in good nick you should be able to start it BY HAND. Certainly can with my TDR.

Meh, 4/10 from me. His explanation of the electrics sucks if you understand electric. Didn't like the woodscrews either, they will be bloody sharp just waiting to catch the wires or worse still your fingers.

I would not go straight for the cdi apart from checking the connections as its generally reliable. Check the cheap stuff first. Because she shares the spark you need BOTH plugs and caps to be good, if one shorts you lose the spark. Make sure the coil is properly grounded and the orange wire to it is good. Make sure the kill switch is good and switched to run (laugh if you like but its been done, a lot). If you try to check for a spark, pull both plugs and just look for the spark on one plug, removing the other.

Nice intro. Welcome to the forum. This is for people like you to say hi etc. To keep things organised pop your question up in a new thread in the workshop section. Plenty of folk will chip in.

You cannot do a compression test on a 2stroke like you would on a car engine. Engine doesn't work that way. You need to do a leak down test to check the crank seals and such. Plug the exhaust (at the barrel) and the inlet again at the red block not at the carb. In either of the plugs you need a bike type valve and a pressure gauge, a tyre pressure gauge will do. Pump some pressure into the engine, not massive pressure 10psi tops. Then see how long it holds. Ideally it wont drop at all. Probably it will drop a bit but if the pressure is gone in the time it takes to have a brew you have problems.

Odd, 40nm is not much. You only get a click to know its tight, past that you can really put some abuse through it (wont help the calibration) as it will act like a decent strong bar and will easily knacker some 6mm nuts.

What are you bringing, the DT with the shooting jacket or the RD.

Always the little things with you eh? Hope it all goes well. My mum has had both done. Best advice. Do the exercises religiously. My dad is a bit of an ocd fusspot with things like that. But for context. Last year my mum needed 2 sticks to get to the loo. As i type this they are on a walking holiday at Grafam Water. She gets about better than i do.

If it was a 2stroke id say 10% off max revs and never wide open throttle past the need for acceleration. Can't see it hurting a clunky old 4banger following the same advice.

Dont think so. The 80 was a bit of a one off. Also watercooled i think. The rd certainly was. If you can find one that is. Their rare enough to restore rather than break. Still only worth buttons afterwards though.

The re will be less restricted. The original pv was king because it made 22hp or so across the channel. Proper power. They were a lot of fun so long as they held together. Cant argue with john on the power/riding style/reliability score.

The easiest to de restrict. Pah. Showing your age. Finers.... The king was the first gen powervalve engine. As quick as yours with the athena kit, properly restricted back in the day. They flew. The rd got the pv first and could scrape 100mph if it was a good one and worked on right.

No point that stuff will get fried. Then the crap will jam the threads. If you are rebuilding a bike thats been stood 20 years you really want to give the engine a seals and gaskets rebuild with new crank and output shaft bearing. While its split give the barrel to the engineers that will probably be reboring it for you anyway and they will have it out quick smart for little or nothing if their doing the bore.

Then with respect your not looking in the right place. With the words "yamaha xvs125 bigbore" google spat pages of info at me including pictures and links to the virago forum for some specific threads. You will absolotely need new barrels. Personally i think its an awful lot of cash for not a lot.