littlerider9
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- Apr 16, 2010
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Ok, i've spent a little more time with the bike, both engines, and even attempted to ride the thing... I suffered a few issues with the bike, specifically the throttle sticking... spent a lot of time chasing the cause of the problem, and have finally found the issue...
Carby/Throttle Sticking:
I had thought it was the quality of chrome facing on the slide, with a small imperfection maybe catching on the bore of the carby... it wasnt sticking with the engine turned off, only when it was running... and would stick at all different throttle settings.. sometimes just off idle, sometimes wide open... not ideal...
So i smoothed the slide with emery paper, no joy there, tried the throttle housing, throttle cable, leaner jetting, different float heights, all sorts of the usual tricks to sort it out... still no joy...
Then i noticed a slight kink where the cable enters the carb top... Those familiar with OKO's will notice that the 26mm fitted to the TTR155z doesnt have the curved carb cap... but a straight holder....
So i swapped the stock cap for one with a curved cable holder, hey presto, no more sticking throttle... anywhere...
For those with a TTR already, if you click this link OKO Australia - Flatslide Carburettors and scroll down, you can find a few different carb caps... the one you want is part # 3050... and sells for $35 from OKO Australia.. cheap permanent fix...
For those looking at a TTR, Russ has already contacted his suppliers for a solution, and will most definately be sorted with the next shipment of bikes...
Jetting:
Despite being very very specific in what jetting Russ wanted, he was supplied with jetting not really that close to what was ordered...
I opened my 26mm up to find a K#45 pilot jet, K44 needle and a K#112.5 main jet.. After testing a few different jetting combinations, i've found the best jetting for the 155z engine to be a K#40 pilot jet, Needle clip on the second groove from the TOP, and a K#102 main jet. This offered easy starting, great response off idle, strong seamless midrange and a very punchy top end. This jetting combination can be sorted with the spare jets offered with the bike in the spares kit. (Bloody good idea that Russ. Brava!!! )
Clutch "Slipping":
One other issue i noticed, that got progressively worse throughout my attempted "first ride" was that the clutch started slipping, until i was getting no drive whatsoever... so here's me thinking i have a brand new motor with a fried clutch... with less than an hour's running time...
Then i noticed the feel at the lever wasnt quite ''right''... a quick look at it revealed that the grub screw for adjusting reach and free play had rattled out a bit, and was constantly holding the clutch slightly engaged... Wound it back out, hey presto, perfect clutch again...
So for those with TTR's, adjust the little grub screw in the clutch perch until you have your desired freeplay and reach, then loctite the grub screw.... lest you end up with a "slipping" clutch like i did... ha ha ha!!!
Fork Action:
The action of the forks are quite harsh, and pretty stiff.. i'm working on a solution for this, so keep an eye on the thread... at this stage i'm thinking it's oil weight and height, i'll be trying a few different set-ups over the coming week, and will hopefully find a happy medium that will soften up the first part of the stroke, while still retaining bottoming resistance...
I'm thinking lighter weight oil, and lowering the height of it...
anyone beats me to it, post up the results in here asap.
Lots of Win:
On the plus side, i've fitted the OKO28mm from the Bling40, and this has transformed the 175 into a real fire breather up top.. the 26mm offered good punch down low, a strong mid range and top end, but didnt offer the usual sting up top that we've come to expect from the OKO flatties.. the 28mm most definately offered that.. just working on cleaning up the transition through the mid range, once i've found the perfect jetting combination, i'll post them up in here as well...
I cannot fault the action of the rear suspension... this thing hooks up brilliantly, and i was riding in wet sand... usually good for sapping power, especially with a small bike, running a small back tyre, and not a huge amount of power..
I thought the bike was perhaps a bit down on power, until a few guys watching commented on how well the bike was squatting under power, and kicking up a lot of debris behind me punching out of corners... So where i'm used to minis that dont hook up perfectly, so they ''feel'' powerful, due to the fact they're spraying gravel everywhere, the TTR hooks up and drives.. oddly enough, much like jap bikes with linkage rears... imagine that...over rough ground, the rear tracks well, and is a stable little platform... only managed a couple of the smaller jumps (cheers rain, how does f*** off sound for next time????) and the rear handled them well without bottoming, and that was with the shock at the supplied factory setting of both compression, rebound, and preload settings, with a relatively quick old fat bloke weighing 88kg on board... so 95% of riders will love the action of the shock and linkage rear...
I've found both the 155 and 175 to be an absolute cinch to start, although the 175 sounds rattly, a common affliction with Z motors...
The clutch action is brilliant, and feeds the power on nicely, which was a bonus on a wet track with deep sand sections... combined with the linkage rear, it's easy to dial on huge amounts of throttle, and drive out of corners without spraying anyone within 20 feet of you with gravel..
Given this is an entirely "new" model and bike, if the issues outlined above are the only ones to crop up, then i think Russ has done pretty bloody well... Small items such as the above were easily and cheaply fixed, and overall don't detract in the slightest, the great value of the bike, nor the quality... Keep in mind, this is the first batch, and the next lot can only be better again!!!
alright, so me any my 2 mates that bought the bikes went riding on the w.e and got about 2 hours of riding done over 2 days.
on 2 of the bikes teh rear brake stopped working, so we adjusted the little rod that pushes the piston in , was working fine, rode for 10 mins, stopped working again so adjusted it more, 10 mins later same thing, so they just rode with no rear brake.
the rear brake pedal on mine kept grabbing on the engine bolt, locking up the back wheel and stalling the bike, evan after i bent the brake pedal out. maybe use the brake pedals that go under the foot peg on the next set of bikes.
on all 3 of the bikes the throttle was sticking on. i know thump said buy a new curved carb cap but i dnt work and have no money at all, and am still trying to pay off the bike, they should have come with the curved cap in the first place
the clutch on 2 of the bikes jsut randomly only pulls in half way, so you cant change gears or come to a stop. i let it stall, kicked it over and was working fine again, this happen to me about 5 times over the 2 hours, wouldnt want that to happen in a race.
the glue on the airfilters is super shitty, and 2 of the airfilters came apart from the rubber mount, there ment to come with aftermarket uni filters but they still havnt shown up.
the wheel bearings in my front wheel and my mates rear wheel shattered, which ended the ride, which wasnt going so good anyway.
and also i found that the rubber seal in the carb bowl stretched after i took the bowl off about 5 times to change the jets, so had to cut the seal in half and cut about 2mm off it so it would fit.
the smart thing to do would have been to get one bike made and shipped over, assemble it, do some solid riding on it for 2 weeks, find out all the faults and get them fixed so customers arnt left with bikes not working properly.
the good things- bike handles awsome! soaks up every bump nicely. with the forks, i drained teh oil and put 5 weight racing oil in them and they are heaps softer and feel heaps better.
