Same noob, new questions ...

[Oldwolf]

First of all, thanks to all of you for setting this up and somehow making and maintaining a helpful and non toxic community. (Gets more rare online everyday)

Secondly, learned the other day these bikes can wheelie, I make the world's least elegant flag, and since I somehow saved it and didn't die. I hope everyone gets thier seven chuckles out of it (I did, after I changed pants .... lol)

QUESTION:
Brozz recon with 250 miles
Changed my oil today from the shipped stuff, to Rotella T4 15-40W. I've now noticed a stutter at WOT with a 5 to 7 MPH drop at top speed. I plan on checking the valve clearance again after work (my engines warm ..... ������ .. riding RULES)
Is there anything else you guys can think of i should look at?

Post got cut off the first time, sorry

[Spins]

Check the valve clearance on a cold engine!

I experienced the same issue with top speed drop with my Brozz after changing out the break in oil and adjusting the valves.

[Megadan]

What did you set the valve lash to, out of curiosity?

As far as the stutter at WOT, and a drop in speed, generally I would say that is related to main jet sizing. If you have any jets on hand, I would start there.

I find it interesting that right at the mile point where our Hawks tend to free up and actually gain a little top end you guys are losing it.

[Oldwolf]

I'm away from my owners manual at the moment, but I think the book says .005.

As far as jets go, the stutter is new since the oil change. I don't mind changing jets, but is the 15-40 enough thicker I should need more fuel? If so, what can I use till I can get new jets?

[TxTaoRider]

Check your spark plug. The stockers are known th have issues.

[gwowzer]

It should be .05mm

[Bill Hilly]

I didn't run the break in oil out on the road, but I did start it up on it several times, and then changed to the 15w40 Rotella. I noticed that the factory oil didn't come up very far in the sight glass while I would hold the bike straight up. I accidentally put a little too much oil in mine when I changed it. It comes up a hair more than halfway on the glass. I didn't take any back out because just barely leaning the bike puts the oil level down to about halfway on the glass. I was pouring from a gallon jug when I did mine. Are you a little over full ? I figure that if one was very much too high the windage may be costing you a little pep.

[Megadan]

The oil is unlikely to cause a sputter during wot. If it were mechanically related, it should present itself outside of a specific scenario like that.

As was mentioned, the valve lash should be .05mm or .002inch. If you set the lash to .005inch, that is rather big on the gap, and could explain a little bit.

I would start by double checking the lash.

[Oldwolf]

I set it to the factory size in the manual, if I added a zero here thats my faulty memory.

I haven't had a chance to check the valves yet, stupid real life getting in the way of my bike ....

Any ideas how much longer I'll have to keep checking valves? Or is that just gunna be a weekly maintenance item?

[China Rider 27]

That motor is breaking in and getting better at sucking air.

[Spins]

Originally Posted by Megadan

What did you set the valve lash to, out of curiosity?

As far as the stutter at WOT, and a drop in speed, generally I would say that is related to main jet sizing. If you have any jets on hand, I would start there.

I find it interesting that right at the mile point where our Hawks tend to free up and actually gain a little top end you guys are losing it.

My bike never recovered from the drop in mph. I’ve changed the oil again and will be soon before I sell it. I installed an Iridium plug and added a Mikuni clone carb. I have a 37.5 pilot and a 115 main, clip on needle jet third from top, air screw 1.5 turns out, removed the air box snorkel and ground down the welds on the stock exhaust header. I’d estimate I’m about 225lbs with full gear. Per GPS I can hit 60mph in 4th gear and 62mph in 5th. I was thinking of dropping the main to 112. Bike runs good and seems to have power, perhaps a little rich.

[gwowzer]

Not to doubt anyone, but.make sure you are setting your lash on a COLD engine on the COMPRESSION stroke at TDC.
I made the mistake once and the bike ran like shit for a.couple days until I figured out what I did. I thought it was carb related at first.

[gwowzer]

Also, your manual will state .05mm for your clearance. That is great if.you set both intake and exhaust to that spec.
Some guys will change it a little, MegaDan could speak more on the reasoning behind that, for example, .07mm-.08mm for exhaust, .05-.06mm for intake. Seems intake runs tighter than exhaust for a reason I haven't grasped yet.
Either way, if you set it as manual says at .05 intake and exhaust, it will be fine.

[Megadan]

Originally Posted by Oldwolf

Any ideas how much longer I'll have to keep checking valves? Or is that just gunna be a weekly maintenance item?

After the initial break in period or a few hundred miles the valve lash only needs a check every couple to a few thousand miles usually. I often give mine a quick check every other oil change, but I don't usually need to adjust them, so no, it's not a weekly maintenance thing.

I mainly just suggested to double check the lash or the reason that gwowzer stated. It's a common mistake that has been made, so I just wanted to cover that base. For all I know it could be ok, but it never hurts to make sure.

As far as the bike running differently as it breaks in, China Rider 27 covered that one rather well. Not only does the better ring seal help draw in the intake charge, it also gets more efficient at expelling the exhaust. The valve seats and valve faces at this point are also sealing just a teeny bit better as well. This can sometimes cause a bike that ran "ok" with almost no miles start to show changes in jetting needs. This effect is also exaggerated a bit if the valve lash was not set from mile 0 and the valves were not sealing before.

As far as a previous question of yours. the 15w40 oil is likely not any thicker than what came in it, which if I understand is 10w40. Both oils have the same hot viscosity, so there isn't any real difference there.

My main goal is to simply try and separate issues so they can be approached individually, if for no other reason than to eliminate one thing to move on to the next. Attacking multiple things at the same time can cause more problems than it solves. So I am starting with the easiest and most likely things first. Valve lash takes a few minutes to double check, and can't hurt anything.

Originally Posted by gwowzer

Some guys will change it a little, MegaDan could speak more on the reasoning behind that, for example, .07mm-.08mm for exhaust, .05-.06mm for intake. Seems intake runs tighter than exhaust for a reason I haven't grasped yet.

The reason behind the exhaust valve often being set wider than the intake in most engines is entirely due to the nature of metal when it gets hot. The intake valve has a cold air-fuel charge rushing by it at high speed, so it doesn't get as hot as the exhaust valve, which has only the contact with the valve seat to cool it after weathering the combustion event and then the supersonic flame fronts blasting past it as it opens. Basically, exhaust valve = hotter. Since metal expands as it gets hot, hotter valve = more expansion.

I set my lash at .05mm intake and .07mm exhaust, but my engine also has way higher than stock compression, port work, a cam, an ignition advance key and an adjustable CDI, so not only do I have a bigger bang from the cam and head porting, but I also have a much higher cylinder pressure from a later ignition event that sends more heat through the exhaust. On a normal CG engine, setting both valves to .05mm works just fine for most people. They can get away with this because the CG runs fairly mild compression, extremely conservative ignition timing, and your basic cam profile for good smooth torquey operation. They don't make a whole lot of heat.

[Boatguy]

From my own n00b experience, I’d say keep an eye on the basics too.

After only 30 miles my chain already needed adjusting. My spokes could use a little fine tuning but I suspect will go out in another couple hundred miles.

Originally Posted by Oldwolf

First of all, thanks to all of you for setting this up and somehow making and maintaining a helpful and non toxic community. (Gets more rare online everyday)

Secondly, learned the other day these bikes can wheelie, I make the world's least elegant flag, and since I somehow saved it and didn't die. I hope everyone gets thier seven chuckles out of it (I did, after I changed pants .... lol)

QUESTION:
Brozz recon with 250 miles
Changed my oil today from the shipped stuff, to Rotella T4 15-40W. I've now noticed a stutter at WOT with a 5 to 7 MPH drop at top speed. I plan on checking the valve clearance again after work (my engines warm ..... ������ .. riding RULES)
Is there anything else you guys can think of i should look at?

Post got cut off the first time, sorry